ABGC Boards: Metabolics Exam Questions and Answers 100% Pass

ABGC Boards: Metabolics Exam Questions and Answers 100% Pass What causes inborn errors of metabolism? - ANSWER -Enzyme deficiencies What causes the symptoms of IEMs? - ANSWER -1. Accumulation of substrate, or 2. Deficiency of product T/F: Individuals with IEMs usually have dysmorphic features - ANSWER -F What is the usual inheritance pattern of IEMs? - ANSWER -Recessive T/F: IEMs usually have effective treatment options - ANSWER -T Why are IEMs common targets of NBS? - ANSWER -Effective, preventive treatments available What is the defect in PKU? - ANSWER -Defect in phenylalanine hydroxylase, which converts phenylalanine to tyrosine What does high phenylalanine cause? - ANSWER -Accumulation of phenylketones What is the most common defect in CAH? - ANSWER -Defect in 21-hydroxylase, which converts 17- hydroxyprogesterone into 11-deoxycortisol What does high 17-hydroxyprogesterone cause? - ANSWER -Virilization in utero What is treatment for IEMs based on? - ANSWER -Correcting metabolic imbalances With IEMs, how much enzyme activity is usually needed to avoid symptoms? - ANSWER -~10% of normal activity 2 | P a g e Created by Grace Amelia © 2025, All Rights Reserved. Which test is better for quantitative analysis of amino acids - plasma or urine? - ANSWER -Plasma What circumstances are best for amino acid analysis? - ANSWER -Fasting specimen What specimen is usually used for organic acid analysis? - ANSWER -Urine Is organic acid analysis qualitative or quantitative? - ANSWER -Can be either! What are examples of clinical scenarios in which amino acids and/or organic acids may be ordered? - ANSWER -FTT, unexplained acute illness, DD, monitoring of therapies for known IEMs What specimen is usually used for acylcarnitine profile? - ANSWER -Plasma How are acylcarnitines usually reported? - ANSWER -By carbon chain length and number of double bonds What types of specimens might be used for enzyme assays? - ANSWER -WBCs, newborn blood spots, fibroblast bx and culture, liver bx, muscle bx What type of mutations do partial activity mutants usually have? - ANSWER -Point mutations resulting in reduced enzyme activity What type of mutations usually result in absence of protein? - ANSWER -Deletions, splice junctions, premature stop mutations What are the pros of enzyme testing? - ANSWER -Less expensive, not dependent on particular mutations What are the cons of enzyme testing? - ANSWER -Enzyme activity may not be stable, enzyme may not be expressed in accessible tissues What are the two types of genetic heterogeneity? - ANSWER -1. Non-allelic/locus 2. Allelic 3 | P a g e Created by Grace Amelia © 2025, All Rights Reserved. What is non-allelic/locus heterogeneity? - ANSWER -Mutations in different genes cause same phenotype What are examples of metabolic conditions with non-allelic heterogeneity? - ANSWER -MPS, methylmalonic aciduria, homocystinuria, propionic acidemia What is allelic heterogeneity? - ANSWER -Different mutations at same locus cause same phenotype What are examples of metabolic conditions with allelic heterogeneity? - ANSWER -PKU What are examples of symptoms in neonatal onset IEMs? - ANSWER --Vomiting -Lethargy -Coma -Severe acidosis (low blood pH) -Respiratory distress -Weakness -Hypoglycemia -Hepatomegaly -Seizures What is respiratory distress in IEMs caused by? - ANSWER -Response to accumulated metabolites What are the general principles that suggest an acutely ill newborn might have an IEM? - ANSWER -- Full term pregnancy -Good APGARs -Non-dysmorphic 4 | P a g e Created by Grace Amelia © 2025, All Rights Reserved. -Normal for first 24-48 hrs Why are babies with neonatal onset IEM usually normal for the first 24-48 hours? - ANSWER - Metabolites need time to build up and baby needs to feed When evaluating an acutely ill newborn for an IEM, what history is important? - ANSWER -- Prodrome -Time until symptoms appeared -Relation to feedings -Lethargy -Vomiting Why might an IEM cause lethargy? - ANSWER -Accumulated metabolites affect brain function and cause sleepiness What is rapid, shallow breathing suggestive of (in IEMs)? - ANSWER -Hyperammonemia What is deep breathing suggestive of (in IEMs)? - ANSWER -Acidosis