Genetics & Metabolic MCQs

Pediatrics · 5 free questions with answers & explanations.

1. A 6-month-old infant of consanguineous parents presents with progressive developmental regression, hyperekplexia, and a cherry-red spot on fundoscopy. He had normal development until 4 months. Enzyme assay shows deficiency of hexosaminidase A. What is the mode of inheritance?
2. A newborn male has ambiguous genitalia. Serum 17-hydroxyprogesterone is markedly elevated. Karyotype is 46,XX. Electrolytes reveal hyponatremia and hyperkalemia on day 5. Which enzyme deficiency is responsible?
3. A 2-year-old boy presents with coarse facial features, corneal clouding, hepatosplenomegaly, recurrent respiratory infections, and developmental delay. Urinary mucopolysaccharide screen is positive. Which of the following distinguishes Hurler syndrome (MPS I) from Hunter syndrome (MPS II) clinically?
4. A child with Down syndrome (trisomy 21) is noted to have a flat facial profile, upslanting palpebral fissures, single palmar crease, and widely spaced first and second toes. Which cardiac defect is most commonly associated with Down syndrome?
5. A 3-day-old neonate has a musty (mousy) odor, fair skin and hair compared to siblings, and later develops intellectual disability. Urine ferric chloride test gives a green color. Newborn screening would have detected this condition by measuring which amino acid?