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NCC Knowledge Nugget Series: Organic Acidemias: El ...
C5-OH ACT Sheet
C5-OH ACT Sheet
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Pdf Summary
The ACT Sheet provided by the American College of Medical Genetics and Genomics is an educational resource for medical geneticists and clinicians. It is voluntary and does not guarantee successful medical outcomes. The resource is not exhaustive and clinicians should use their professional judgment in determining the appropriateness of specific procedures and tests. They should also consider the date the resource was adopted and other relevant medical and scientific information. Intellectual property interests may restrict the performance of certain tests and procedures.<br /><br />The ACT Sheet focuses on newborn screening for elevated C5-OH Acylcarnitine, which is associated with a group of organic acid disorders. These disorders result from deficiencies of enzymes involved in the breakdown of branched-chain amino acids. Clinical presentations vary, and potentially toxic metabolites can accumulate. MCC deficiency is the most common disorder, while HMG and HCS deficiencies can present acutely in the neonatal period.<br /><br />Immediate actions recommended include informing the family of the screening result, assessing the newborn's clinical status, consulting with a pediatric metabolic specialist, evaluating the newborn for hypoglycemia, ketonuria, and metabolic acidosis, and initiating confirmatory/diagnostic testing as advised by the specialist. The family should be provided with information about possible diagnoses and their management, including the need for urgent treatment of metabolic acidosis. The final diagnostic outcome should be reported to the newborn screening program.<br /><br />Diagnostic evaluation involves measuring plasma acylcarnitine levels and urine organic acids, performing urine organic acids and plasma acylcarnitine tests on both the infant and mother to evaluate for maternal MCC deficiency, and considering other tests such as serum biotinidase and plasma amino acids. Enzymatic and molecular genetic testing may be necessary.<br /><br />The clinical considerations highlight that MCC deficiency is usually asymptomatic, while HMG and HCS deficiencies can present acutely. Other conditions can manifest with hypoglycemia, lethargy, and hypotonia during infancy and/or childhood. Treatment options are available for each condition.<br /><br />Additional resources are provided for communicating newborn screening results, emergency protocols, gene reviews, and condition information for families. Referral options include finding a genetics clinic directory and using the genetic testing registry. Local, state, regional, and national resources are available.
Keywords
ACT Sheet
medical geneticists
clinicians
newborn screening
elevated C5-OH Acylcarnitine
organic acid disorders
MCC deficiency
HMG deficiency
HCS deficiency
diagnostic evaluation
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