Welcome to the ACMG Adult Genomics Case Conference hosted by Emory University. Here are the disclaimers about this strictly educational resource for clinical geneticists. ACMG does not warrant the accuracy, completeness, or timeliness of the information presented. The planning and organization for this webinar series is from the Adult Genetics SIG Webinar Group and the Education Committee of the ACMG. The disclosures for the members of the special interest group. And our presenters today are from the Emory University School of Medicine. I am Dr. Jaime Vengo Echea. I'm the adult geneticist here, and I'm accompanied in today's webinar by Dr. Rosanna Sanchez, who is our biochemical fellow, Christine Tallo, certified genetic counselor, who's our cancer genetic counselor, Dr. Hong Lee, who is our metabolic specialist, Dr. Rafaei Khan, cardiologist and electrophysiology fellow, and by Laura Beam, who is our Ph.D. and associate professor of genetics at the Molecular Genetics Lab. If you have signed up for educational credits, you will get questions at the end of this presentation, which will explain how to claim that credit. To ask a panelist a question, you can type your question into the Q&A box, and the questions will be answered verbally by the panelists at the end of their own presentation. The learning objectives of this series are to recognize cardinal signs and symptoms of specific genetic conditions commonly seen in the adult genetics clinic, discuss appropriate diagnostic tools and molecular testing strategies in adult patients, recognize the challenges and limitations in ordering genetic testing in adults, and describe the utility of whole exome sequencing in adults and its application in the care of the adult genetics patient. For this particular session, we want you to be able to, at the end of this session, recognize the difficulties in assigning a specific phenotype to a known pathogenic mutation in a case of sudden cardiac death, review the clinical differential diagnosis for sudden cardiac death, describe the challenges in diagnostic testing for hereditary melanoma, describe the counseling considerations of identifying a mutation in a predisposition gene, recognize alert signs that can point to a metabolic disorder in an adult, and review the clinical presentation of covalent deficiencies. So the first case will be presented by myself, Dr. Kahn, and Dr. Bean. This is the case of a 48-year-old man who presented with sudden cardiac arrest. He was previously healthy, and the patient did note that his heart rate has always been in the lower range. After defibrillation and resuscitation at an outside institution, an implantable cardiodefibrillator device was placed. After his event, we obtained an EKG that will be reviewed by Dr. Kahn in a few minutes, but basically showed a QT interval of 382, which was normal, a slight upsloping of the ST in V1, which was not classified for Rugada syndrome, a possible epsilon wave in V1, and an inverted T wave in V3 with a flattened T wave in AVF. EKG changes felt to be nonspecific and not suggestive of any particular disorder. The family history had no relatives with known arrhythmia or sudden cardiac death, and a 29-gene arrhythmia panel was ordered by the cardiologist. Here is the pedigree showing our patient who had sudden cardiac death and bradycardia. His parents both had MIs in their 70s and are living. There are two paternal, a paternal uncle and a paternal aunt who died of stroke, and the patient's son also has bradycardia. He's 20 years old. Dr. Kahn will now describe the EKG findings. So this EKG essentially showed an atrial pace rhythm, and this atrial pacing rate was set at 60, so his intrinsic heart rate was probably less than 60 when this was put in. The other interesting findings on this EKG was that there was a slight closing of the SD segment in lead V1, and possibly a slight epsilon wave sort of at the end of the QRS complex at the beginning of the T wave in lead V1, and this seemed to be slightly more prominent in the second beat of the V1 lead. There was also some nonspecific SD changes with the T wave inversion in lead 3, but overall, I mean, this was not classic for Bugatta or for ARVD. So to sort of understand what may have caused this presentation of sudden cardiac death in this patient, we focused on three major differential diagnoses, the first one being Bugatta syndrome, the second one being Long QT syndrome, the third one being ARVD, and I'll sort of talk about them briefly. Bugatta syndrome is essentially an autosomal dominant, primarily autosomal dominant transmitted inherited channelopathy and causes electrical dysfunction in the generation of the action potential, and this is sort of manifested in EKG by a prolonged QRS duration and clinically by sudden cardiac death. It's mostly seen in males, the mean age of diagnosis is about 41 years of age, and it's primarily seen in Asians. The major genetic abnormality tends to be loss of function mutations affecting the sodium although other channels such as the potassium channels and calcium channels have also been described, but their frequency is a lot less. But primarily this genetic channelopathy affects the epicardium and the endocardium differently, so say you have differences in the action potential duration between the epicardium and the endocardium. What that does is it sets a re-entrance circuit between the two layers and the generation of ventricular arrhythmias. Clinically, as I mentioned, it's manifested by either syncope or V-fib or sudden cardiac death, and interestingly these are triggered by certain environmental factors such as fever, cocaine, or class 1A antiarrhythmics. The EKG is interesting in that it has three predominant patterns. Type 1 pattern, as you see on the top in the left part of the figure here, has a large coved ST segment elevation followed typically by slight T-wave inversion in one of the two V1 or V2 precordial leads. Type 2 and type 3 are essentially saddleback patterns, and depending on how much the ST elevation is, you can classify them as 2 or 3. Interestingly, if you were to give them a class 1A or class 1C drug such as flaconide or flaconone, you could potentially induce a type 1 pattern, and that would be diagnostic of Brugada syndrome. Their management essentially involves the implantation of an ICD, especially if it has sudden cardiac death. Moving on to Long QT syndrome, this is sort of a collection of cardiac channelopathies that affect the repolarizing currents of the action potential, and there have been approximately more than 500 mutations involving 13 different genes, but 75 percent of them are accounted by the first three types of Long QT syndrome. Long QT1 and Long QT2 are essentially loss-of-function mutations in the potassium channel. Long QT3 is essentially a gain-of-function mutation of the sodium channel, and this can sort of lead to increased depolarizing currents and increased action potential duration as a result of that. Each three has their own individual EKG pattern. As you can see on the right here in the figure, Long QT1 has a broad-based T wave, whereas Long QT2 has a saddleback T wave, and Long QT3 has a prolonged QT that's secondary to a prolonged isoelectric segment. Clinically, these are manifested by, again, prolonged QT in the EKG, syncope or torsades, and sudden cardiac death. And again, in this disorder, it's interesting that there is a genotype-specific trigger such that Long QT1 is typically triggered by the physical exertion, and Type 3 can be seen at rest or while sleeping. There are essentially two modes of inheritance with variable penetrance. The dominant disorder is the Romano-Ward syndrome, which is an autosomal dominant transmitted disease, whereas the more severe phenotype, and unfortunately less frequent, is the Gervais-Lange-Nielsen disorder, which is associated with sensorineural deafness. Treatment of these disorders primarily involves the use of beta blockers, but again, if they've had sudden cardiac death, that buys them in ICD. ARVD, or arrhythmogenic live ventricular dysplasia, is characterized by fibro-fatty replacement of the RV myocardium and RV myocyte loss. It is, again, primarily an autosomal dominant transmitted disease, although there is a more severe autosomal recessive component as well, which is called the Naxos syndrome. That's typically characterized by woolly hair and increased keratosis of the palms and the feet. The main genetic abnormality essentially involves the genes involved in the desmosome proteins, which are essentially proteins which allow for cell-to-cell coupling in the heart, and with these genetic abnormalities, you essentially have loss of electrical coupling and mechanical coupling of the cells in the RV. Clinically, this is also manifested by sudden cardiac death and ventricular arrhythmias, and you may be able to detect this on an EKG if you see either inverted T waves in these V1 to V3, especially after the age of 14, and as well as by the findings of epsilon waves, which are small little potentials seen at the end of the QRS and at the beginning of the T wave. This finding is seen in about 30 percent of patients, but one found is highly specific for this disorder. The management of this disorder essentially involves the avoidance of competitive sports, the use of beta blockers, and again, if they've had sudden cardiac death, they get an ICV. So, the cardiac arrhythmia panel showed a heterozygous sodium channel 5A mutation, a substitution resulting in an early termination codon, and therefore was described as a pathogenic variant, but the report could not say what syndrome this variant was pathogenic for, and as we will see in a minute, there are good reasons behind that. The phenotypes related to this particular gene usually, in activating mutations, present as Brugada syndrome type 1. Usually, gain-of-function mutations present as Long QT syndrome type 3, and biallelic mutations of sodium channel 5A have been reported in families with sick sinus syndrome. And, as we saw from Dr. Kahn's presentation, the patient's electrophysiologic phenotype does not clearly fit into any of these categories. So, now, Dr. Beam will describe the interpretation of these panels. So, because the patient's electrophysiological phenotype did not exactly match what we would expect for Brugada syndrome and a nonsense change in SCN5A, we wanted to look a little more closely at this change and see if there were any red flags that may indicate that this change is not, in fact, causative of disease. So, we looked at the large population studies and found that this change, as expected, is not observed in the population. There were a few rare truncating variants in EXACT in this region, but nothing that would suggest that loss-of-function variants around this amino acid were okay. And we did note that this loss-of-function variant, this nonsense change, is in the last exon of the gene. When nonsense variants occur in an mRNA, they typically lead to nonsense-mediated decay of the mRNA and no protein being produced. However, if that nonsense change is in the last exon or the next to the last exon, you could have escape from nonsense-mediated decay of the RNA, resulting in the production of a truncated protein. So, it's possible that a truncated protein is being made, but this has not been tested and it's not something that we can predict. We also looked in the literature to see if this particular nonsense change had been reported before, and we found two reports. The first, in Benson et al. in 2003, goes with this pedigree right here. The proband was a 10-year-old who was identified with absent P waves, pauses up to 15 seconds in an escape rhythm at 50 beats per minute, and a prolonged QRS interval. The nonsense change, as seen in our patient, the arginine 1623X, was inherited from the maternal side. Maternal relatives who all had an asymptomatic first-degree heart block. There was also a missense change identified on the paternal side, but the most likely interpretation for this missense change is now benign or likely benign. So, it's most likely that this nonsense change is causing the phenotype in this family. The second report was in 2005. This is a 65-year-old man with recurrent syncope due to sinus arrest. First identified at age 61, and after faintness due to ventricular fibrillation at age 65, he was successfully resuscitated, and his ECG showed a coved type ST segment elevation. So, the presentations of these two probands were different and not exactly what was seen in our patient either. One interesting point about nonsense changes in SCN5A, they are most often associated with Brugada syndrome. You can see all the nonsense changes lined up here, going from the 5-prime end of the protein all the way through to the 3-prime. However, there are nonsense changes that are associated with Long QT syndrome, with cardiac conduction disease, as well as this arginine 1623X, which was class of 6 sinus syndrome from that 10-year-old proband. Most of these disorders are caused by nonsense changes towards the 3-prime end of the protein, and as I mentioned, if they're occurring in the last exon or the next to the last exon, it is possible that a truncated protein is being produced. This is not something that we can predict whether an abnormal protein or lack of protein is being produced without a protein study. So, this is something to keep in mind, and it highlights the challenges of genotype-phenotype correlations. So, attempts at genotype-phenotype correlations must be made with caution, particularly when only one or a few probands have been reported with a particular variant, even if it's a loss-of-function variant. We must be cautious as well if a gene is associated with more than one distinct phenotype, and if those phenotypes are complex. And always remember that speculation and assumption as to what the clinical outcome for a particular gene will be could be incorrect or harmful. In this case, a gene panel was more efficient than trying to go a single gene at a time because there are varied phenotypes associated with each of the genes for conduction defects. And, as always, molecular results must be interpreted in the context of an individual's clinical and biochemical features. So, as Dr. Bean showed, one of the previous reports for this particular variant was in a family with sick sinus syndrome. Sick sinus syndrome is actually characterized by SA node dysfunction with marked sinus bradycardia, less than 50 bits per minute, and nonspecific symptoms such as dizziness, fatigue, confusion, and syncope. The EKG manifestations are often intermittent, and this is usually seen in the elderly. Recessive mutations in sodium channel 5A can cause congenital sick sinus syndrome with bradycardia progressive to atrial arrest. And there have been families reported, as seen before, with apparently autosomal dominant sinus syndrome, which throws another differential into this patient's clinical presentation. So, how did we manage this particular case? Well, first is the patient already had an ICD placed, so we didn't have to make a clinical decision regarding that. If possible, we would like to test his elderly parents. The PNOVO mutation would be strong evidence for clinical correlation. That is to say, this sodium channel 5A mutation is the true culprit for this patient's phenotype. The best phenotypic fit is likely to be BRUGADA1. Also, call in mind the 65-year-old case that was described by Dr. Bean earlier with the co-type ST changes, our patient did not have a classic BRUGADA1 syndrome EKG, which has created all our difficulties with management. But we could avoid class 1C antiarrhythmic drugs, including fleconide and profafinone. Class 1 agents, such as procainamide and disoperamide, and also avoiding fever or febrile states should be treated early. However, sick sinus syndrome remains in the differential, and it is a reasonable recommendation to tell this patient to avoid beta blockers. Finally, we have the difficulty of how to test at-risk relatives. The mutation is clearly pathogenic. We just don't know what it is pathogenic for. We must first properly counsel the relatives that the phenotype in the family has not been clarified before suggesting any genetic testing. A careful analysis of the relative's EKG will be necessary. If Bradycardia is present, a Holter monitor or a loop monitor may be placed, as these patients may have sick sinus syndrome, and this may help clarify the diagnosis and catch some of those intermittent ECG findings. However, if there is none of this history, then we may need to induce with sodium blockers an electrophysiologic study to unmask the Brugada type 1 ECG in relatives that test positive. So, we would like to open this for questions, which can be sent into the text box at any time for the first group of presenters. Well, it appears that there are no questions for this particular case. Oh, we have one. So Claudia McHale asks, have insurance companies been amenable to covering the multi-gene panels? It is really kind of hit or miss. Some companies have been amenable, generally for indications such as arrhythmia that have the potential for sudden cardiac death they are, especially if you can make a good argument that this can change management. Even in cases where an ICD has been placed, such as our patient, you can make a good argument about treating fever early and other recommendations particular to the syndrome. So generally this can be covered. Any other questions? You can just type them in the text box. Nara Simhan from Integrated Genetics asks, was a follow-up testing Brugada using a psyllium channel blocker such as Fleconide performed? Dr. Khan? No, it has not been performed on this patient yet. There is some discussion about whether to bring him in or to do one. I don't know how much it would change his management because he has already received the ICD. But to establish a definitive diagnosis by seeing a coped type 1 pattern may actually help his children more and offer them better genetic counseling. I think we are trying to get in touch with the children to see if they can come in and sort of be involved in that. Jordan Pringle from UCSF asks, please repeat the name of the syndrome of the foul diagnosis. So it is the working clinical diagnosis for this case is Brugada syndrome type 1. And one last question, Dr. Tayoom from the University of Pennsylvania asks, we have seen that the last exon in SEM5A is significantly enriched for truncated variants in EXACT compared to cases. Any comments about that, Laura? There were several in EXACT, but as I recall, not this particular variant, and I don't recall how frequent they were, but it did not, if there is an enrichment, it is not that this exon is not important, it is that some truncating or frame shift variants are allowable. Okay. Thank you for your questions. We will now move to the second case. And the presenters for this case will be myself and Christine Tallo, who is our cancer genetics counselor here at Emory. So the case is that of a 46-year-old woman who presented with a vaginal melanoma. Melanomas of the vagina represent 0.3% of all melanomas in women. The family history was notable for a maternal aunt that died at age 29 with metastatic cancer. Her sister was diagnosed with breast cancer at age 36, and then diagnosed with a vaginal cancer, although it is unclear if it was melanoma, and then leading to diffuse metastatic disease. Despite many attempts, it has been very difficult to clarify the sister's personal history. There's also a family history of pelvic cancer in two female first cousins affected in their 30s, however this has not been confirmed, and a multi-gene panel was ordered for mutations in genes associated with breast cancer, ovarian cancer, and melanoma. Here is the pedigree for this family. As you can see, our proband was diagnosed with a vaginal melanoma. Her sister was diagnosed with breast cancer, and there is a maternal aunt with an unknown cancer that died at age 29, and the two maternal first cousins who had reportedly ovarian or possibly pelvic cancer in their 30s. So, what was our differential diagnosis after seeing this particular pedigree? The possible hereditary cancer syndromes that were considered, among those that we would label as high-risk genes, BRCA1 and 2, because of the presence of breast, ovarian, and melanoma in this family, a question mark around ovarian, but this will be our assumption, P10 with the family history of breast cancer, early-onset breast cancer, TP53 with breast cancer and these unknown cancers in other relatives, TDKN2A, particularly because of melanoma, and Lynch syndrome with a history of endometrial cancer, ovarian cancer, and breast, which may or may not be linked to Lynch syndrome. In the moderate-risk genes, CHECK2 has been linked to breast and colon. There's breast cancer in our family. The ATM heterozygous have an increased risk for breast. We don't believe that this family represents a homozygous case of ATM, but could well represent a heterozygous case, and PALB2 with the family history of breast cancer. Some lower-risk genes or susceptibility genes that were considered in the presence of melanoma, particularly the BAP1 gene, CDK4, TERT, MITF, and MC1R. So based on this somewhat broad differential diagnosis, and with the limitations of the family history that we were able to obtain, we selected a next-generation sequencing panel that includes the genes that you can see on your screen, and the results of the test showed that the MC1R gene had a heterozygous variant classified as pathogenic. The inheritance as reported in the result was both possibly dominant or recessive. And then there were two variants of unknown significance. A variant of unknown significance in CDKN2A that was heterozygous and reported as having dominant inheritance, and one in MSH2, also heterozygous, also reported as having dominant inheritance. So some of the difficulties with the interpretation. In a similar fashion to the first case presented today, the results were not reported according to ACMG guidelines, which say you should report the gene, the variant, the classification, and the inheritance, but in this case, not for what disease. MC1R can be as best described as a risk factor or a susceptibility gene. Therefore, the variant may be pathogenic, as reported, but it's only pathogenic for susceptibility to melanoma. The risk associated with MC1R is about 1.67-fold with a NODS ratio, and therefore not what we would call a high-impact gene. CDKN2A variants have a frequency of – the CDKN2M variant found in our patient has a frequency of 0.22%, and it, importantly, has been reported in one individual with melanoma who also happened to have an MC1R mutation. Again, the report does not state the boost for what disease, and we should focus on the possible phenotypes related to CDKN2A, such as melanoma strocytoma syndrome. We know that the pathogen for melanoma is as high as 76% by age 8 in the U.S., but 93% in Australia indicate an important component. The pathogen for pancreatic cancer is 17%, but only one common mutation was analyzed in this particular report, and that the pathogen for astrocytoma has not been well-reported. Do MC1R and CDKN2A, then, together, add up to the risk of melanoma in our patient? Is this digenic inheritance, or are we just seeing a slice of a polygenic inheritance? Our current models and definitions of mechanisms of inheritance do not capture this risk correctly, where one gene contributes a little bit and another gene contributes a lot, and effective communication of these results to the patients becomes a challenge. The second question is, is this finding clinically actionable? The patient was advised to have annual skin exam. However, this would have been the case whether we had reached this underlying genetic diagnosis or not. Christine will discuss some of the counseling issues. So, as Dr. Domingo-Chea just described, these results, while interesting, do not impact the overall treatment plan for the patient. Again, at this time, it is unclear whether the patient's pathogenic mutation, MC1R, actually contributed to her melanoma diagnosis. Again, we're not certain if it's interacting with her variant in CDKN2A to impact her melanoma risk. Of course, whenever we are seeing patients to discuss variants of uncertain significance, we want to emphasize that they should stay in contact with their provider or their genetic counselor if these results were ever reclassified in the future. And particularly in cancer counseling, patients are not only concerned about their own cancer risk, but their risk for their relatives. Of course, we always want to consider whether results of genetic testing would change management. In this case, just based on family history alone, the patient's siblings and adult children should already be using standard skin protection precautions and have annual skin exams, so their results were not likely to impact their medical management at this time. Another factor that would impact testing of relatives would be cost and insurance issues. The family has socioeconomic challenges, and would testing for these particular variants be worthwhile for them right now? In addition, the patient is the primary caretaker for her sister, who is currently going through treatment for breast cancer and has fairly progressive disease. For the patient's relatives, we would recommend to wait to undergo genetic testing until the VOOC in CBKN2A is better defined. Now the patient's sister, who was diagnosed with breast cancer in her 30s, is an appropriate candidate to undergo genetic testing for herself. At the time we initially saw the patient, her sister had not yet undergone genetic testing. But of course, testing for her sister should focus on genes potentially associated with early-onset breast cancer, like the ones Dr. Vengochea described before, including BRCA1 and BRCA2. A challenge when collecting family history for this patient was that we were not able to review her sister's medical record to determine if her diagnosis of abdominal cancer was related to metastatic breast cancer, or if that was a new primary cancer. Finally, while the patient's own test results do not explain why her sister did develop breast cancer at such a young age, it is reassuring that it rules out a mutation in major breast cancer susceptibility genes in the patient. And I was just recently told by a colleague here in Atlanta that the patient's sister is currently undergoing genetic testing for herself. So, now we would like to open the second case for questions. Again, you don't have to wait until we are done with the case to write your question in the box. Well, it appears that there are no questions for us with this particular case. So we'll move to our third presentation today. Dr. Hong Li, assistant professor at the Department of Human Genetics, is going to discuss inborn errors of metabolism in adults, and Dr. Rosana Sanchez is going to present a case of inborn error of metabolism. Okay, let's switch gears to the inborn error of metabolism in adults. The objectives of this presentation is to reveal the difficulties and the red flags in recognizing IEM in adults, and to increase the awareness of the IEM in adult populations. So why is it difficult? First, as we all know, the diagnosis and care of patients with IEM has been the realm of the pediatrician. So the misconception of inborn error equals early diagnosis always exists. In the adult medicine and the physicians barely thinking about a metabolic disease. Second, IEMs are individually rare, especially adult IEMs are even rarer because most of them are unrecognized and undiagnosed. The field physicians encounter them during practice, and that's the low exposure. Field physicians are trained in the field of adult inborn error of metabolism, and even for metabolic physicians, most are receiving the pediatric-based training. IEMs are usually presented in a different way in adults than in children. They always display the attenuated phenotype compared to the classic picture described in children. The other thing is in the adult population, a lot of IEMs are misdiagnosed as idiopathic or atypical form of the other common disease. As we all know, when a patient is carrying a common disease diagnosis and the physician stops digging in the real etiology, and the diagnosis can be missed. Why this in the IEM can be presented late? Usually in the adult IEMs may have higher residual enzyme activity because they're different mutations, and also could have the modifier gene effect to play the role. Some adult IEMs have shown very mild clinical presentation in the early ages, but they remain undiagnosed because of their nature of the mild presentation, soft during the presentation. Some diseases have been screened for many years, but the mild form still can be missed even when we do the newborn screening. Dietary self-limitation, by their experience, can change the disease causes. Some adult IEMs can mimic the common disease and remain undiagnosed. The other important concept for IEM is the age of presentation is also determined by the metabolic stressors. They can be asymptomatic until the body was hit by severe metabolic stressors, such as illness, surgery, injury, some medications, starvation, and pregnancy in a female. What's the red flags in recognizing IEM in adults? What organs could be affected? And the major organ system involved is the nervous system, and they're presented with neurological and psychiatric presentation. But other organ manifestations can include cardiomyopsy and liver disease, especially those non-alcohol fatty liver disorder, and without the risk factor. We know obesity can be caused by that, but if there's no risk factor, and that's a red flag. So, if you have a neurology presentation, and a particular eye or skin findings, that can give you the clue. So, as we mentioned in the adult IEM presentation, and essentially neurological and psychiatric, and the typical situation will be a patient presented with this neurological psychiatric problems, but it's unexplainable, and it's very bizarre. And so, usual workups have been done, and they rule out the usual etiologies. That's something we should think about in the IEM. So, the following list is the common presentation. They can present a typical psychosis, depression, and the recurrent comas, and ataxia, and stroke, especially those pseudo strokes. So, in order to better remember the conditions, to remind us, and I give this in the place mass spectrum order, and to better remember this. So, the involved aero metabolism often presented in the recurrent episodes, or the symptoms are fluctuating, and they're usually triggered by metabolic stressors, as we mentioned before. And some patients, when we do the specific imaging study, and there is a suggestive, and the findings based on the pattern and the location, should raise the concern for IEM. And a lot of them can be presented as the uncommon presentation of the common adult diseases, such as stroke. They happen early. They're very atypical, and they're imaging, and it doesn't correspond for the uro-arterial territories, and the hypertension, and the dementia, and the psychiatric problems. Of course, when we treat the patient, but there is a poor response, or even worse, and to the standard treatment in that situation, we should also consider the IEM. Family history, and maybe at the beginning, is not suggestive, but when we take a closer inspection, and may indicate in IEM, and with the various presentation in other family members, especially those X-linked in the IEMs, it should be considered. Slow progression, and may suggestive for isosomal storage disorder, or paroxysomal disorder, so the detailed asking question, and may disclose the evidence of the problems in children, in childhood, or adolescence. And if the patient presented in the symptoms regression, or cognitive decline over time, that's another red flag. We always think, and neurologically, the major presentation, but if patient presented with diffused systemic involvement, and that's a, we should consider IEMs, such as, not only in the neurological presentation, but also has other system, and the involvement, other signs, and then you can detect it. Even the presented in neurological presentation, they can have the unusual pattern involved a different part of the nerve system. If luckily, and the patient, by careful exam, you may find that the signs with very high diagnostic value for IEM, such as angiokeratoma, and is suggestive for fibroids, and the cherry red spots, and may be suggestive for isosomal disorders. So, what's the general approach? I think to keep the high index of the patient of IEM is critical, and our goal is do not miss the treatable disease. So, based on the patient presentation, as long as we think about the metabolic, and the certain lab workup, or imaging workup, can be ordered based on patient presentation. The following, and we are going to have a case presentation by Dr. Sanchez to better understand and how to apply this, and the principles in evaluation of patients with IEM. Good afternoon. So, now we will briefly depict a case that would basically highlight some of the signs and symptoms that Dr. Lee was just discussing. So, we present the case of TA. This is a 33-year-old man with a past medical history of mild cognitive impairment, but he presented with an acute mental status change. He was unresponsive. Basically, he was comatose, and he was also having fever. So, on studies, at admission, he had CSF studies done, which were normal, and a culture in the CSF was eventually normal as well, as well as some viral studies. He had a blood culture that was negative, and he did have a urine that grew in pterococcus fecalis. Of further questioning, it was noted that seven months ago, he had started having seizures. The seizures were described as generalized tonic-clonic, and also as staring episodes. He had a total of 11 events at the time, and he was treated with Keppra. And at this same time, around the same time, he was having some cognitive decline. So, the mother described him as being more clumsy than usual, less alert, less active, and having some memory problems. Additionally, he was having some difficulty ambulating by himself. So, he started having to use an aid to actually help him walk, and he was started on physical therapy. So, with these two things happening, one with a more insidious course and one that was more acute, the working diagnosis on admission by neurology was an acute over a subacute encephalopathy of a known origin. Now, it was thought that maybe there was a component of an infectious disease, but another thing that differential was rheumatologic disorders, and one of the considerations was actually pancreatitis nervosa. So, with this initial presentation, we digged in further in the past medical history, and we actually uncovered that he had early onset seizures. This had started at around one year of age, and he had been seizure-free for about 20 years at this time. Of AEDs, he was initially treated with phenobarbital. When they did the evaluation for the seizures, they found out that he also had megaloplastic anemia. And so, this was also of a known origin, and it was treated with phenylcobalamin intramuscularly and with folic acid, but the patient just decided to discontinue these meds in his early 20s. He also had, at the time, hypotonia and had delay of motor and, we think, also speech milestones, but the mom wasn't very clear in telling us, you know, when he started doing several things. So, we only know that he, for sure, walked late at around 30 months of age. And then, finally, the family history was non-contributory. So, on admission, this is what the initial labs showed. So, he had a CBC that clearly shows megaloplastic anemia. So, his hemoglobin was 9.5, which is very low. His MCV and MCH were both elevated. He had a normal B12 and a normal folic acid in blood. It was not the RBC folate that was done. And as part of a stroke workup, he actually had a homocysteine done. Now, the number is above 50 because that's the cutoff for that specific test, and that's when, actually, genetics was involved. There was more of a workup done at the time. There was an ammonia level, which was normal, lactic acid, which was normal. And we, of course, reviewed all of the other studies as the CSF studies. So, at this point, we also reviewed his imaging studies. We uncovered that the brain MRI was not normal. There were hyperintensities both in the periventricular and the subcortical white matters, and there was also volume loss in the brain MRI. The spine was normal, but as you can see here, the EMG and the nerve conduction studies were actually abnormal. There was sensory and motor neuropathy and peroneal palsies that were bilateral. And finally, the EEG didn't show any seizure activity, but there was background slowing overall in the study. So, we started our own metabolic workup at this time. And so, what we uncovered at the time was that when we sent the total homocysteine in plasma, this was actually very elevated, so the cutoff is 13.8. And the patient had 268 micromoles per liter. Additionally, the plasma amino acids showed a very low methionine of 5, with a cutoff of 21 in the lower side, and the MMA was actually normal. So, with this biochemical profile, then we gave our own differential diagnosis, which included the primary remethylation disorders. And so, in this group of disorders that have this similar biochemical profile, we included the methionine synthase reductase, also known as cobalamin E, methionine synthase defect, also known as cobalamin G, nicobalamin D variant 1 defect, and MTHFR deficiency. And as you can see, MTHFR deficiency is lower in our list, although all of these cause the neurological symptoms. This one doesn't typically give you the hematologic conditions, present very severely and very early. And so, in the bottom of this slide, you can see this pathway. And so, you have the – I'm sorry that it came up different – but you can see that there's impairment here in the remethylation of the homocysteine to methionine via the methionine synthase. This is the enzyme, and it uses methiocobalamin as a cofactor. But for it to be in its active reduced state, it needs a second enzyme, which is the methionine synthase reductase, which is right here. So, if there's deficiency of this enzyme over here, it causes cobalamin E deficiency. And if there is a problem with the methionine synthase, it causes cobalamin G. And you can see over here, up here, in a different pathway, just incorporating right here, where the cobalamin D variant 1 defect is. So, you can see where all of these are located, that it will give you the high homocysteine with the reduced methionine, and basically, there's a normal MMA associated with this. And they all present very similarly. All of them clinically overlap. And so, we continued the workup for our patient, but in the meantime, we wanted to do emergent treatment. This is something that we shouldn't stop until we have molecular confirmation. With the biochemical profile, it's enough for us to treat. So, we started the hydroxyl cobalamin intramuscularly. We started betaine at a lower dose, 6 grams per day, folic acid, B6, and aspirin. And these are our therapeutic goals. So, we wanted to correct the hematological and the biochemical parameters, try to normalize the methionine levels, lowering the homocysteine and trying to prevent thromboembolic events, and finally, trying to see if we could improve the neurological symptoms on our patient. And so, in the meantime, we got the molecular testing back. And so, what we found was two pathogenic variants in the MTR gene, and this is the one that encodes for the methionine synthase enzyme, which causes cobalamin G, so this was our final diagnosis. Both of these variants, pathogenic variants, are known and are described in other patients with the disease, and take into account that we sent a very large panel to obtain testing for this disease. And at follow-up, the patient responded well. He was more alert, ovulating and talking independently. The homocysteine is not on target yet. It's still elevated, but better. The methionine is increasing, still a little lower than CARA, and the CBC is also improving, but still needs some increase in the hemoglobin and decrease in the MCV and MCH. We adjusted at this follow-up debutane, and we recommended some therapies. And so, very briefly, cobalamin G is a rare inborn error of intracellular cobalamin metabolism, and it usually presents in infancy and childhood, as was the case with this patient. The most frequent symptoms that you see are hematological, but we don't understand a lot of times the natural history of these disorders, especially how they would present in an adult who was treated at a time and then stopped his medication. So, we're assuming this abrupt decompensation was due to that. And finally, some highlights of the case are that it's important to recognize patients who were initially missed the diagnosis in childhood, also that, as Dr. Lee pointed out, the signs and symptoms of these are usually fluctuating, that there's neurological manifestations, and there could be many CNS manifestations at the same time, but also take into account when there's diffuse disease. So, the systematic involvement of the CNS, but also another one, like hematological in this case with the megaloblastic anemia, and, again, the important point of not missing a treatable condition. So, now the Q&A for this case. Well, will folks think about any questions that they may have related to any of the presentations today? Oh, we do have a question coming in. Do you know why he quit taking cobalamin in the first place? Actually, no. This was a patient who we are assuming was lost to follow-up for many years. He hadn't been seeing genetics or neurology prior to this episode, and this was something that he just decided to discontinue by himself without any medical advice. That was the time of teenager time, and so teenagers can decide by themselves. And this is a frequent problem in adult metabolism, patients that turn 18 and do not have a good understanding of their condition, and tend to forget or were never told how important certain medications were, and don't realize that they have to keep taking this almost as a life-saving medication, even if it's a simple vitamin. And also for the metabolic condition, because a lot of them have the psychiatric as a component to neurology kind of presentation, so sometimes they don't have a good ability to make a right decision. That may also play a role in this case. So Yuan Xue asks, what molecular test did you order, Dr. Sanchez? So we ordered actually a very large panel of genes for inborn errors of metabolism. In Georgia, if you have state Medicaid, it's a little bit hard to offer testing in other states, and it's usually not approved by Medicaid, but we can order testing within our system. And so there's a very large panel of genes that includes all of the different intracellular metabolic metabolism genes, and so we had to go for a bigger panel instead of a smaller one, although we kind of knew what we were trying to settle for in the diagnosis. This also happened in other metabolism conditions, like GA2, and we know there are three genes, but barely, and they offer the panel. GA2, we offer the three-gene panel, but the similar phenotype, the biochemical phenotype, can cost by other transporter genes, and currently there's no lab that offers that, and sometimes we have to go very broad in the panel test. So Carolyn Farrell asks, as far as the clinical cases, could certain personal habits impact lower frequency of symptoms, such as dietary supplements? And I guess she's talking about, for example, self-restriction of protein in OTC carriers or, you know, similar, possibly subconscious decisions to avoid certain... Yeah, this is also important, you know, when we ask a question and when we suspect in some inborn error metabolism, especially protein-based disease, like amino acid disorder, urea cycle disorder, and if the patients, the parents, and they learn about their experience, when they take in more protein, they feel sick, so they kind of self-restrict their diet. That also can change the disease course. I should add that some of the over-the-counter supplements might not be ideal for some of these cases, so even in complementation studies, for instance, in the cobalamin deficiencies, it has shown that the cyanocobalamin doesn't act the same as the hydroxycobalamin, and the hydroxycobalamin form is IM only, and it's the one that we typically use for the treatment of these patients. So it might help, let's say, if they were taking a supplement just over-the-counter biomass, it might help a little bit the biochemical profile, it might help a little bit the hematological profile, but it shouldn't correct it altogether. Okay, so in conclusion for today's webinar, we would like to highlight that even though these three cases were not diagnosed using exome sequencing, they were all based on next generation panel sequencing, it is still very important when ordering these panels to have a predetermined differential diagnosis rather than going on a hunting expedition, because often you will not be able to line up the genetic test result to a particular phenotype. Also, some of the challenges we face in adults in terms of loss to follow-up for the family or difficulty in identifying relatives, often we will read test reports that say, can test parents to see if this variant is de novo, and it's very difficult to do that in adults, and some of the challenges in long-term follow-ups for adults with metabolic conditions. So with that, we would like to thank you for your attendance and conclude the webinar.

recognizing inborn errors of metabolism

difficulties in identifying adult IEMs

red flags for potential IEMs in adults

vaginal melanoma

genetic testing

MC1R gene variant

acute mental status change

cobalamin G defect

long-term follow-up of adult patients