Repeated USMLE Questions Step 1- Review- 147

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Q- A 3-year-old boy has recurrent infections, thrombocytopenia, and eczema. Labs show prolonged bleeding time and low IgM. Which mutation is most likely responsible?

A-Adenosine deaminase deficiency

B-Bruton tyrosine kinase mutation

C-CD18 gene defect

D-WASP gene mutation

D-WASP gene mutation- Wiskott-Aldrich syndrome (eczema, thrombocytopenia, recurrent infections) is due to a mutation in the WASP gene → defective cytoskeleton reorganization in immune cells.

 

Q- A newborn has a continuous machinery-like murmur. What embryologic structure failed to close?

A-Bulbus cordis

B-Ductus arteriosus

C-Foramen primum

D-Truncus arteriosus

B-Ductus arteriosus- A persistent ductus arteriosus produces a continuous “machine-like” murmur.

 

Q- A 22-year-old woman has heat intolerance, weight loss, and tremors. Labs show ↓TSH and ↑T3/T4. Which autoantibody is responsible?

A-Anti-centromere antibody

B-Anti-microsomal antibody

C-Anti-mitochondrial antibody

D-TSH receptor-stimulating antibody

D-TSH receptor-stimulating antibody- Graves’ disease is caused by TSH receptor–stimulating antibodies, leading to increased thyroid hormone production.

 

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