Hello, I hope that everyone hears me okay. So my name is Sirisak Chan-Prasad. I'm a clinical genetics attending physician in Adult Genetic Medicine Clinic here at University of Washington. And good morning according to the Pacific time and welcome to the Adult AZMG Genomic Case Conference hosted today by University of Washington Adult Genetic Medicine Clinic and Division of Medical Genetics. So the next slide is a disclaimer and I have to say that this webinar is intended as an educational resource and AZMG does not warrant the accuracy, completeness or timeliness of the information presented in this conference. Next slide is Adult Genetic Spatial Interest Group and their disclosures. So you can see all the people that work hard to make this happen. So presenters for today gonna be four of us, myself, Sirisak Chan-Prasad and Emily Malouf and Lauren Perrier. Both of them are clinical genetic counseling in our clinic and Dr. Michael Dorchner, Laboratory Director of the Center of Precision Diagnostic here at University of Washington. Of all of us, we will have no relevant financial disclosures. However, I will discuss about the off-label use, the IV arginine to treat acute mitochondrial decompensation. So and everyone, please complete the evaluation at the conclusion of the webcast and if you paid for the CME credit, as you register, you will receive your certificate. So this session learning objectives. At the conclusion of this activity, you should be able to recognize the cardinal signs and symptoms of specific genetic conditions seen in the adult genetics clinic and discuss appropriate agnostic tools and molecular testing strategies in adult patients with genetic and metabolic conditions. And recognize challenges and limitations in interpreting molecular genetic testing results in adult patients with genetic conditions and discuss appropriate measures in managing adult patient with metabolic diseases. And you can type your question into the Q&A box and we will have someone to look at that question and then put it down and the question will be answered verbally by us at the end of the presentation. So the outline of this conference. First, we will introduce our practice in adult genetic clinic here at University of Washington. And then we have three cases. The first session is a two non-cancer cases that's gonna take about 30 minutes. And the second session is a one cancer case. And then we will have question and answer session for about 10 minutes. And we will have a concluding remarks for the last part. So to give you an introduction to our adult genetic practice at the University of Washington, the UW Genetic Medicine Clinic was founded in 1959 by Dr. Arnaud G. Motowski, the first division head of medical genetics in the Department of Medicine. And it is the only comprehensive adult genetics clinic in six states, as you see in the picture, Washington, Oregon, Idaho, Montana, Wyoming, and Alaska, covering 25% of the U.S. And it is the largest adult genetic clinic in the country and we have integrated clinical care research as well as education for more than 50 trainees per year. And areas of expertise include neurogenetics, Huntington disease, center of excellence, connective tissue disorders, dermogenetics, cancer genetics, cardiovascular genetics, and recently we have added metabolic and mitochondrial diseases in the area of our genetic clinic expertise. And the practice size, well, we locate at the UW Medical Center and Seattle Cancer Care Alliance. So this graph show you the number of patients that we have seen. You can see that for the past several years, the total number is about more than 2,000, but half of that is gonna be cancer genetic patients. And we have seen broad variety of pathology, including neuro, autism, cardiovascular, and other. So this picture of us here at Genetic Medicine Clinic, but this is the old one. So it's not include all of us, but right now we have 11 clinical geneticists and six genetic counselors and three supportive staff. So I just came here. So my picture is on the side, but we will have the new picture soon. So I will present the first case. Again, my name is Sirisak Chan. I'm a clinical genetics attending physician at the University of Washington Division of Medical Genetics. Today I'm gonna present adult metabolic disease. So the patient is a 42-year-old female who has a remarkable prenatal delivery and developmental history. And she had been in her usual state of health until the age of 19, when she developed viral illness, followed by poor feeding, nausea and vomiting, and neurological symptoms characterized by confusion, abnormal movement, and seizures. So she was admitted to a hospital in Michigan where she and her family lived in 1994, and she had extensive workup, including MRI of the brain, which show hyper-intense lesions in the basal ganglia and thalami bilaterally, as well as at the gray-white junction in frontal occipital cortex. She also had brain biopsy that showed neuronal loss and gliomatosis. And muscle biopsy revealed muscle fiber atrophy and denervation, as well as abnormal mitochondria. But there was no mention about electron transport chain being performed, and no hallmark of mitochondrial myopathy shown, for example, like no mention about bracket-red fibers or Cox negative fibers. So at that time, mitochondrial disease, probably Lee syndrome, was suspected, and she got better slowly. Oh, we didn't do spectroscopy on the MRI at that time, like 20, 30 some years ago, so just only MRI that showed hyper-intense lesion in the basal ganglia. So she got better slowly over time, but she continued to have abnormal movement, choreoacetyl movement, especially on her left side. Then she moved to Seattle, and at the age of 38, she was admitted to UW Medical Center for acute lavishial field distortion, followed by paresthesias of her extremities at increased cognitive difficulty. So at that time, the MRI of the brain showed features consistent with basal ganglia stroke, and there was discussion between neurologists and neurogenetics, and believed that this patient might have mitochondrial encephalopathy-like the acidosis and stroke, or MILAS. So the decision was made to give her IVR gene, and she responded beautifully, and she was discharged. At the outpatient follow-up, molecular genetic testing was performed for the mitochondrial DNA mutations, the common ones, including those associated with MILAS, as you can see, and they were all negative. So this is the family history. Pretty unremarkable, she has a younger brother who is now 37 years old, and he is alive and well, living in London, United Kingdom, and both of the parental ancestries are Northern European. So she's a college graduate, and she does not work, she's on disability, she lives with her parents, she does not smoke, drink alcohol, or use illicit drugs. So she has symptoms, but been stable for years, but continues to have correolithosis of the extremities, left more than right, and she's been taking medications, which is mitochondrial cocktail, including coenzyme Q10 and riboflavin. So on physical exam, her general appearance, she's appeared in no acute distress, and heart and lungs normal, abdomen soft, not tender, and no liver or spleen enlargement. On neurological exam, for the cranial nerves, she has facial dysplasia, but otherwise normal. She has a normal light touch and pain temperature, but slightly decreased vibration sense in the lower extremity. She has no focal weakness, but when she walks, she has a wide-based gaze, and she has increased tone on the right side. So this is the MRI performed about four to five years ago when she was admitted, suspected of stroke-like episode at UW Medical Center. So this MRI showed a T2-weighted image, and then you can see hyperintensity lesion in the central part of the caudate nuclei, bilaterally. And this here, there is some hyperintensity lesion on the flare image, so you can, this one is in the occipital lobe, but you can, for another cut, there's some like a few scattered throughout. So in summary, this patient, a 42-year-old female, previously healthy, developed sudden onset of neurological problems characterized by encephalopathy, extrapyramidal movement disorder, and seizures. So all of these preceded by viral illness. She has never returned to normal baseline and has had few exacerbations since onset. So at that time, we made a differential diagnosis. So the major one that we think about is a mitochondrial disease, most likely Lee syndrome and MILA. So what is Lee syndrome? So Lee syndrome, or subacute necrotizing leukoencephalopathy, is a genetically heterogeneous group of mitochondrial disease caused by a defect in nuclear mitochondrial DNA. So the age of onset, usually within the first year of life, around like a three to 12 months, and late onset or adult onset have been well-documented, but may be underdiagnosed. In classic form, children develop normally until they acquire viral illness, mostly peripheral upper respiratory tract infection or viral gastroenteritis, and then they develop severe gastrointestinal disturbances like poor feeding, nausea, vomiting, and failure to thrive, and followed by psychomotor regression, extrapyramidal movement disorder, and cerebellar ataxia. Disease is relentlessly progressive and usually die within a decade of a diagnosis. So in adult onset form, the clinical features tend not to be homogeneous like the classic form. So the precipitating factors might not be present. Patient can have mild to moderate developmental delay early on, and can have psychomotor retardation, cerebellar ataxia, and extrapyramidal movement disorders. They might not have the acute attack like childhood or classic onset form. In biochemical features, the elevated lactate in blood and CFS is present, and neuroimaging show hyper-intense lesion on T2 in the basal ganglia brainstem, and periaqueductal gray, which is quite specific for the Lee syndrome. So the next disease that we start with discussing about is MILAS. This is one of the most common mitochondrial disease known to human, and it is caused by a defect in mitochondrial DNA. The age of onset of stroke-like episode is between 10 to 40 years old. The stroke-like episode outside this timeframe is very rare. So clinical features, so as the name implies, stroke-like episodes is the defining feature of this syndrome. And I should point out that one who have, patients who have MILAS mutation, not everyone will develop MILAS. Only patients that have stroke-like episodes, we will consider it to have MILAS syndrome. So other common features include muscle weakness and myopathy, seizures, and migraine, and other less common findings include hearing loss, diabetes type 2, short stature, and cardiomyopathy. So biochemical features, we can see elevated lactate in blood in CSF, but CSF is more persistently elevated in blood. And on muscle biopsy, we can see racket red fibers, which is abnormal mitochondria when we look at under microscopy with staining by Gomory trichome, and racket blue fibers, which is a proliferation of mitochondria under the SDH staining, and COX negative fibers. And patients can have abnormal electron transport chain. And neuroimaging, so during the acute attack of stroke-like episodes, the MRI will show features that we can see in stroke patient, which is a restricted diffusion with images on MRI, but it's not in the area that usually see in a classic stroke, because it's not conformed to any vascular territory. So the usual location is parietal temporal lobe. And the treatment, so there has been many studies evaluating the underlying pathogenesis of stroke-like episodes in MILAS, and all of them found that during the stroke-like episode, the patient with MILAS syndrome have significantly lower levels of nitric oxide, which is a potent vasodilator. And with that premise, so we started giving the patient with arginine, which is a precursor of nitric oxide. And not surprisingly, the arginine IV during the acute episode increased the level of nitric oxide in the bloodstream, and then shortened the duration of the stroke, and decreased the severity of it. And now we know that if we give oral supplementation of arginine or citrulline between the episode, it can reduce the frequency and severity of stroke as well. So in dealing with mitochondrial disease, it is very difficult to diagnose because they have protein clinical manifestation and involve all organ system. In the old day, we tend to do muscle biopsy and look for the hallmark of mitochondrial abnormality on the muscle biopsy specimen. As I mentioned earlier, COX-negative and SDH-rich fibers, record-rate fibers, or we are doing electron transport chain assay. But now we have molecular genetic testing tool that is less invasive. So if we see a patient that have symptoms very specific to well-described mitochondrial syndrome, we can do a target analysis by doing point mutation or just like a small panel. However, most of the time, we don't have that luxury. So we can do comprehensive dual genomes for mitochondrial disease or whole exome sequencing. So in this patient, we decide to do dual genomes for the mitochondrial genome and nuclear DNA that have been associated with mitochondrial disease. And interestingly, we found compound heterozygous likely pathogenic variant in SLC19A3 as listed. So is this a likely pathogenic variant according to ACMG standards? Because these two variants affect in functional domain and are not enlarged databases. So we look at ClinVar and XF, we could not see any published of these two variants in the database. And it's a predicted deleterious effect and in a disease that is a highly specific phenotype, which I will discuss it on the next slide. So mutation in these genes cause a disease called biotin and thiamine responsive basal ganglia disease or BTBGD. It is a relatively newly metabolic disease discovered about like 10 to 20 years ago. First described in the Bedouin tribe from the Middle Eastern. The age of onset typically is about three to 10 years, but neonates or adult patient with this condition have been well documented. So the clinical features, the patient tend to develop normally and acquire viral illness and have recurrent neurological signs and symptoms, including seizures, extrapyramidal movement disorder, apexia, ophthalmoplegia. And when you exam during the acute attack, all of them will exhibit corporeal rigidity. And the diagnosis is made by the brain MRI that show bilateral and symmetric increased T2 signal intensity, especially in the central part of the caudate nuclei, putamen, thalamus bilaterally, and some area of the infra and supratentorial brain cortex. When you do like a diffusion wave imaging, so you can see the vasogenic edema during the acute crisis at the same position. And molecular genetic testing show pathogenic variant in SLC 1983. So taken together, we believe that this is the diagnosis of this patient because she has a quite clear common clinical features, a common MRI findings, and likely pathogenic variants on the SLC 1983 according to the ACMG guideline. So pathophysiology of this disease we still not fully understood, but this gene encodes thiamine transporter two, but biotin and thiamine not deficient in plasma. So thiamine is a cofactor of pyruvate dehydrogenase complex enzyme, which is a very important enzyme generating acetyl-CoA used to fuel tricyclic, sorry, Krebs cycle. So deficiency of this transporter might have a defect in transporting thiamine into the cell and then cause energy deficiency. And evidence suggests that high dose biotin increase the expression of this transporter. So the treatment option during the acute attack, we give high dose thiamine IV about 2000 milligram per day total. So it can be like 1000 milligram twice a day and biotin five to 10 milligram per kilogram per day. And during the maintenance, so thiamine 300 to 900 milligram per day and biotin five to 10 milligram per day. So treatment in this patient, we give her thiamine 900 milligram per day and biotin five milligram per kilogram per day, which is a 400 milligram per day. So in the case, all the case report, if we diagnose early and treat with high dose thiamine and biotin during the acute attack, the patient, almost all of them tend to resolve with this condition and then return to normal baseline. And then when we give like a thiamine biotin as a maintenance doses, they have a reduced frequency of the acute attack. So follow up her for about like one and a half to almost two years, she never had any attack again and her symptoms have been stable. So take home point, metabolic and mitochondrial diseases very difficult to diagnose. We have to have high index of suspicion. And when we see a patient with encephalopathy with abnormal movement disorder precipitated by viral or other illness, an MRI of the brain review lesion in basal ganglia. I think it is reasonable to try treat this patient with high dose biotin and thiamine because it's easily available and not very expensive for these two medication. And molecular genetic testing right now the path is biochemical testing, but again, muscle biopsy is sometimes useful. Okay, so we're gonna shift next to the case two. Hello, my name is Emily Malouf. I am a genetic counselor here at the Adult Genetic Medicine Clinic at UW. And I've been here for about four years. Today I will present a case that has, that led us or taught us to really appreciate the complexity of Wardenburg syndrome. I'll discuss the clinical aspects and Dr. Dorschner will discuss the molecular aspects. And so with this case, we will look at Wardenburg syndrome beyond the white forelock. So we were referred a 31 year old woman with a personal history of progressive neuropathy, severe sensory neural hearing loss, and some additional medical issues. And the referral, she clearly has a complicated medical history. The referral asked us to consider or evaluate for a possible genetic etiology. Focusing on her neuropathy history around age 23, she was diagnosed with progressive neuropathy. In April 2016, an EMG showed very slow nerve conduction velocities, consistent with symmetric demyelinating sensory motor peripheral neuropathy of the arms and the legs. In September of that same year, a neuromuscular evaluation here at our institution showed slight facial asymmetry, exotropia of the left eye, significantly reduced sensation to pin, light touch and vibration up to the thighs, as well as in the hands, and also noted a mildly ataxic gait. Because these features were suggestive of Charcot-Marie-Tooth or CMT, the neurologist sent an initial genetic test for PMP22, which was negative. So that ruled out duplications, which is the cause for CMT type 1A, which accounts for the vast majority of CMT type 1. And it also excluded deletions in this gene, which causes HNPP or hereditary neuropathy with liability to pressure palsies. So excluding these common causes and sending the patient to us for further evaluation. We did note her lifelong hearing loss. She was diagnosed with hearing loss at 18 months and given hearing aids. She attended special schools for those with hearing impairments. In young adulthood, she noted that her hearing got worse from baseline. The imaging in 2015 was quite significant. A brain MRI showed two things. First, congenital malformation of the semicircular canals bilaterally, as well as bilateral small appearance of the basal turn of the cochlea. And also bilaterally, no clear demonstration of the cochlear nerve, suggesting a small caliber. Given these findings, soon thereafter she was fit with a right cochlear implant. And other medical history for her included constipation, which she often self-treated with self-digital disimpaction, as well as GERD. She shared that she lacked a sense of smell, but that had not been formally tested, and other things such as astigmatism and panic attacks. Her physical and neurological exam with us, the findings were very consistent with the reported history and our review of the records. We noted normal mental status, no changes in pigmentation, no abnormalities of pigmentation. She did have slight asymmetry of the face with left ptosis and left exotropia. She had high arched feet. Her sensation was reduced, primarily in the lower extremities. We noted mild heel-to-shin ataxia, also reduced reflexes in the ankles, and also noted slight-based gait and difficulty balancing. Her family history in this picture, unfortunately, has been skewed just a bit, but she is of European descent, and you'll see that it's otherwise pretty non-contributory. We note that she said her maternal grandfather had neuropathy, but that was actually at an older age. She had a maternal half-aunt, she said, with neuropathy, though we don't have very many details about that. A maternal aunt with hearing loss and hearing aids, though that was at an older age. She shared that she thought her dad had neuropathy, but he had not been formally evaluated. Of note, we do not see any congenital hearing loss. We do not see any early-onset neuropathy, and we don't see any other features that we see in our patient. Our differential consisted of a few things. First, perhaps she could have a syndromic CMT that would explain her neuropathy, as well as something that included hearing loss. There are some subtypes of CMT that have hearing loss. We see that with CMT-4b2, and we see that with CMT-2j. We also considered the possibility that she had two separate conditions that were unrelated, one form of CMT, as well as a separate genetic or another cause for her hearing loss. We considered CHARGE and Kallman syndrome. She had a few features that we see in these conditions, though she was not characteristic for either one of those in their full clinical description. With the CHARGE, we see the ear abnormalities and hearing loss. With Kallman syndrome, we see lack of sense of smell, so anosmia. In doing a search for neuropathy and the inner ear abnormalities found on her MRI, we came up with possibly a variant of Wardenburg due to genetic alterations in the SOX10 gene. We ordered testing, which included over 200 genes associated with neuropathy, and we also included the gene associated with CHARGE, and that testing was done on an exome backbone. Our result for her was diagnostic. We identified, or the lab identified, a pathogenic variant in SOX10, which was a premature stop. She was heterozygous for this. I'll touch briefly on SOX10, but Dr. Dorschner will talk more about this specific result. SOX10, the full name is SRY-related HMG-BOX10. It is a transcription factor. It actually is involved in neural crest development, and it's involved in the development of the melanocytes and intestinal ganglia. It also is involved in inner ear development. SOX10 causes a form of Wardenburg, so a summary of Wardenburg syndrome, we see three primary things in Wardenburg syndrome. Brain loss, for most, it is bilateral or sensorineural. We see that in the vast majority of individuals with Wardenburg. We also see pigment disturbances in their hair, in their skin, in their eyes. In this picture, it's a good demonstration of this white forelock. In individuals, we might see different colored eyes. In Wardenburg syndrome, another characteristic feature are inner ear malformations, such as enlarged vestibular aqueducts or malformations of the semicircular canals. This condition accounts for 2 to 5% of all individuals with congenital hearing loss or congenital deafness. It is inherited in an autosomal dominant pattern, though it is quite clinically and genetically heterogeneous. In general, we think of it as having four subtypes, as shown over here, but there are also six genes of note. The same gene can cause both type 1 and 3. And also, genetic alterations in SOX10 can cause both type 4 and type 2, so again, highlighting the clinical and genetic heterogeneity, there is significant inter- and intrafamilial variability. To review all known conditions associated with SOX10 genetic alterations, I just explained earlier, or just a moment ago, that there is a subtype of Wardenburg type 2. There is a subtype of Wardenburg type 4. There is also a separate condition called PCWH. P stands for peripheral demyelinating neuropathy. The C stands for central dysmyelination. The W stands for Wardenburg syndrome. And the H stands for Hirschsprung disease. And so, because of this kind of wide clinical spread, we think it's actually more useful to think of these conditions more as SOX10-related disorders, as opposed to these different clinical subtypes. Now, all of these, in their descriptions, do share the three common findings of Wardenburg syndrome, the hearing loss, pigment abnormalities, and inner ear abnormalities. I noted that dystopia canthorum is absent in these subtypes. Specifically, that is displacement of the inner canthi, shown in the picture, the previous slide. In training, we think of dystopia canthorum as classic or characteristic of Wardenburg syndrome, but this is a good example that not all subtypes have this particular finding. But SOX10-related disorders also have these neurologic abnormalities, olfactory deficiencies, so anosmia due to olfactory bulb agenesis, and also GI findings. So our patient really has four of these main findings, the hearing loss, the inner ear abnormalities, the neurologic abnormalities, and the GI abnormalities. I put question marks next to the pigment abnormalities because we didn't appreciate any on a physical exam, though we may not have been looking closely enough. It was quite subtle, though we did ask if she was aware of any changes in pigment, if she dyed her hair or anything like that. We just didn't notice any when we met with her. But also, she reports the anosmia or lack of smell, but that was not formally evaluated. In general, we think she fits best into this PCWH, though there is overlap with these conditions. So she seems to fit best in this SOX10-related disorder spectrum. So we met with her to discuss these results, and we explained this SOX10-related disorder as an explanation for her features. We discussed the reproductive implications and the variability and really the uncertainty. We recommended things that she's sort of already doing, continuing to go to neurology for follow-up and treatment of, or management of the neuropathy and the balance problems. We recommended a GI consultation for constipation. We were quite satisfied having identified a genetic diagnosis for her features, though she felt, it seemed that she felt a bit, it was a bit anticlimactic, didn't meet a whole lot of changes for her, specific changes for her. So reviewing a follow-up note from when she met with her PCP soon after that, her doctor noted, she got some answers from genetics this fall as far as her neuropathy, hearing loss, even her GI symptoms. She has a variant of Shaw-Wardenburg. This provides some relief and satisfaction. Now she knows it's all related and why. So I'll just turn the time over to Dr. Dorschner to discuss the variants and the molecular findings. Hello, I'm Michael Dorschner. I'm the Laboratory Director for the Clinical Genomics Section at the Center for Precision Diagnostics. We perform primarily exome and genome-scale sequencing for clinical diagnostics. As Emily mentioned earlier, this test was performed as a panel-on-demand in which we allow providers to select a set of genes for testing. This is generally performed in exome background. In this particular case, the SOX10 variant that was reported is currently not seen anywhere in the literature, nor has it been published in the NOMAD database. The majority of variants in this particular gene that cause disease result from premature termination codons. There are a few missense variants, but most are loss of function. This diagram here was taken from a paper published by Jim Lupski's group at Baylor, and this describes some of the loss of function variants that have been seen in SOX10. Those PTCs found upstream of exon 5 typically generate a less severe phenotype, or form of Wardenburg, referred to as type 4. In these instances, variants cause disease through the mechanism of haploinsufficiency, in which variant transcripts are targeted by nonsense-mediated decay for destruction. In the case of variants that are found in exon 5, these tend to produce protein truncation products because these transcripts escape the nonsense-mediated decay process. The variant indicated there in blue, the tyrosine-388-2X, is the variant that we found in this particular patient. It's located in the transactivating domain at the C-terminus of the protein. Let's see. Protein termination codons in the last exon produced a truncated form of the protein with a dominant negative activity, and as you can see from the previous diagram, those variants that were found at the 5' end of exon 5 tend to cause more severe phenotype, as Emily mentioned earlier, referred to as PCWH. Those premature termination codons in the internal exons upstream of 5 tend to cause disease through haploinsufficiency, and the reason that the truncating or the truncated forms of the protein produce a more severe phenotype is because they still have an intact high-mobility group. This is the part of the protein that allows the transcription factor to bind with the DNA motif that it targets, and these proteins have a higher affinity for this target than do the wild-type forms of the protein, and thereby they outcompete the wild-type protein for access to the DNA, and the problem with the truncated variants is they also lack or are disrupted at the transactivating domain there at the C-terminus, and without an active transactivating domain, recruitment of other transregulatory factors are not able to be completed properly, and you cannot initiate transcription of the gene at that point. So, these tend to cause a more severe phenotype, and this particular variant is consistent with what we saw in this particular patient. I'll turn this over to Lauren. All right. Okay. I'm Lauren Puryear. I'm a genetic counselor here at the University of Washington. I'm going to talk through this final case pretty quickly so that there's time for questions at the end about any of the three cases. This patient is a 29-year-old man who was referred to us for one of our most common referral indications, which is a family history of a hereditary cancer syndrome. In this case, it was Lynch syndrome identified in his sister following her diagnosis with uterine cancer at age 30, and interestingly, no one else in the family has had genetic testing yet. The patient's sister was diagnosed in 2015, so it's been a couple years, and neither of her parents have pursued testing, and our patient is now just coming into clinic. So, the family history, you can see on the paternal side, there is a colon cancer diagnosis, a bladder cancer diagnosis, at earlier ages than we would typically expect in the general population. In the maternal side of the family, there's one individual with both colon and bladder cancer, but at later ages, and there's this maternal aunt who passed away in her 50s from some type of cancer. If that was colon or uterine cancer, this would be a more suspicious maternal family history, but given the information that we have, we're not entirely sure which side of the family this MSH2 variant came from. You can see in the youngest generation in this pedigree, our patient, who's 29 with no history of cancer, his sister, who has this molecular diagnosis, she has the pathogenic MSH2 variant, and she also had a variant of uncertain significance identified in BRF1, which we talked about a little bit with our patient in the appointment. And then, the patient has another sister who passed away in her early 20s with a history of three different malignancies. The patient was a kid when a lot of this happened, so he doesn't know what type of leukemia she had or what treatment she was given, so we don't know if that sister had an increased risk for a secondary malignancy due to her treatment for leukemia. But even if that were the case, colon cancer isn't the most common secondary malignancy that we would see in that type of situation, so we were a little bit concerned about that very young diagnosis. And specifically, we talked with the patient about a very rare condition called constitutional mismatch repair deficiency, just so that we could offer him a little bit more testing if he was interested to make sure we weren't missing something in this family history. So, for an individual who has a single pathogenic variant in MSH2, you can see the cancer risks here, very high lifetime risk for colon cancer, also very high risk for endometrial cancer for anyone who has a uterus. You can see the mean age of onset, and that our patient's sister, who was diagnosed at age 30, was certainly below the average age, although not outside the range of what's been reported. And bladder cancer is also part of the Lynch Syndrome spectrum. It's listed here as urinary tract cancer, which also includes cancer of the ureters. For an individual who has two pathogenic variants, biallelic variants, in one of the mismatch repair genes, they have a different phenotype, which also includes very high risk for cancer, but more beginning in childhood. So, the phenotype externally doesn't show much, except for cafe au lait spots, that's very typical. Almost all reported patients have had at least one or two cafe au lait spots, and some have had lots. But the increased risk of malignancy, particularly for brain tumors and gastrointestinal tumors and hematologic malignancies, just made us a little bit concerned that this patient's sister could have had an undiagnosed hereditary cancer risk, and we didn't want to test him for a single MSH2 mutation and miss something else that might be going on in the family. So, the patient was happy to do a larger test, and we had to problem solve a little bit with paying for that test. His insurance wasn't on board with looking for a very rare, slim possibility. And so, we ended up doing a panel test for him at a different lab than where his sister was tested. And what came back was that he did not carry the known MSH2 variant found in his sister. He did carry the BRP1 variant, and the laboratory that his testing was performed at classified it as a likely pathogenic variant, rather than a variant of uncertain significance. So, this particular BRP1 variant is a splice site variant. The labs, all three labs that have listed this in ClinVar agreed that it was predicted to lead to an in-frame deletion of an exon in a functionally significant region. The laboratory that called it a VUS also added that there is a known variant in this same region that significantly reduces BRP expression in the nucleus. So, it has the functional effect that this variant in our patient is predicted to have, but it's common in the general population. So, they weren't entirely sure that this BRP1 variant would actually cause an increased risk for cancer. However, I will give you the update that I looked this morning in ClinVar, and the VUS entry is gone. So, as of two days ago, this is updated, and we now, it looks like now there's agreement that this is likely pathogenic. So, what does that mean for our patient who carries it? Well, he doesn't have to worry about ovarian cancer because he doesn't have ovaries, which is the primary risk that is associated with BRP1 pathogenic variants. There's some disagreement on female breast cancer risk. There aren't any guidelines, really, for patients in terms of increased breast cancer screening at this point. The NCCN guidelines only deal with ovarian cancer, but this is also a gene in which biallelic pathogenic variants cause Fanconi anemia. So, our patient is 29, and he may have plans at some point in the future to have a family. And so, for him, the real significance of carrying this variant is that he's a carrier for an autosomal recessive condition that he might want to think about as a reproductive risk. So, as a quick reminder, Fanconi anemia features are listed here. Congenital malformations are very common, occasionally developmental delay, and bone marrow failure and hematologic abnormalities are very, very common. Generally, everyone who is affected has some sort of hematologic abnormality. And then tumors are also more common than in the general population. So, our summary for this patient was that he carries a BRP1 variant. He should be aware of the reproductive repercussions, but it's only a risk if his partner also carries a pathogenic or likely pathogenic BRP1 variant. We also recommended that based on his family history of colon cancer, on both sides of the family, and particularly in his sister at a very young age, and we weren't able to do any genetic testing in her because she's deceased, that he should consider himself as having an increased risk based on family history. He should certainly not follow Lynch Syndrome guidelines because he doesn't have Lynch Syndrome, but because of the sister's diagnosis, we recommended following first-degree relative diagnosis under the age of 50 guidelines from the NCCN, which are listed here. In terms of family follow-up, we encouraged him to talk to his parents about testing and to contact us if they had questions about testing. And we did say that if he really wanted to track down what had happened with his sister who'd passed away, you know, we have occasionally been able to track down tissue from someone who had surgery for a tumor and do genetic testing on that tissue. So, I'm waiting to hear back about whether that's something the family is interested in. Given that the parents haven't even pursued testing for themselves, I'm not anticipating that they'll want to do that. So, take-home points for me from this case, really confirmed family history information. I think we got a few more details that changed our thinking when we talked with the patient. We consented this patient very carefully. We talked about the BRP1 VUS that was found in his sister because we knew doing a larger panel test, it might show up again on his report. We did not warn him that it might be classified differently. We didn't consider that possibility, but we did a good enough conversation about unexpected potential results that that was not a problem. And he was fine with the uncertainty because we kind of had that discussion about what could, you know, what do we know and what do we not know. And for him, that was a very comfortable place to be, that, you know, we don't know everything and he felt better sort of having a sense of, you know, the context for what we were telling him about these variants. All right. So, now we're presenting all of our three cases and if you have any questions, just type in and I got two questions about my cases that I will answer. So, the question number one, in retrospect, do you think that response to arginine was spurious? And the other question is, how do you explain response to IV arginine and if she had another attack, would you include it in the treatment plan for her? So, I can say that it is difficult to say whether she responded to IV arginine because in mitochondrial disease patients, they tend to have acute exacerbation of neurological deterioration, mimicking stroke, not just only in the MILAS patient, like the Lee patients that I have discussed previously. So, it is not uncommon to see the abnormality on the brain MRI in the basal ganglia that's typically seen in stroke patients. But we use arginine to treat MILAS patients only because we have evidence to suggest that there is a low nitric oxide concentration in MILAS patients. But we never did a study in other diseases, other mitochondrial diseases, so we don't know whether they have the same pathophysiology during the acute exacerbation and mimicking stroke. So, like I said, I think it's very difficult to answer, but I wouldn't be surprised if the arginine helped other mitochondrial disease patients other than MILAS that have like some stroke like in the basal ganglia. But in terms of her treatment plan, if she develops another acute attack, I will not include the IV arginine in this patient because she already has a probable most likely diagnosis, which is the BT-BGD, and the treatment plan is like a thiamine and biotin. I think that we can do these two medications without using IV arginine. However, IV reserve using arginine in patients whom I don't know a diagnosis and very suspected of mitochondrial disease, even if not a MILAS patient. Okay. Do you have any more questions? Okay. So, people should do evaluation and submit so that you can claim the CME and you can just... Okay. And if you don't have any questions, I would like to close this session by thanking all of the speakers. So, I'm not going to thank myself, but I'm going to thank Lauren and Emily, who are genetic counselors here, and Dr. Michael Doshner to provide insight about molecular genetic testing and also Dr. Hisamah, our director in adult genetic medicine clinic, and also for her kind to get everything done and also screen for the question forum. Okay. So, thank you very much for your attention.

neurological symptoms

mitochondrial disease

Lee Syndrome

MILAS

IV arginine

Lynch Syndrome

MSH2 gene

Wardenburg Syndrome

genetic testing