Repeated USMLE Questions Step 1- 213

A 4 year old boy is brought to his physician by his mother. She is worried and tells you that her son is weak and not developing properly. He chews his fingers and lips constantly and seems to enjoy it. On examination, there is marked loss of tissues on his fingers and lips. His serum and urine uric acid are elevated.

What is the most likely diagnosis of this condition?

A-Gaucher disease

B-Hurler syndrome

C-Lesch-Nyhan syndrome

D-Galactosemia

E-Tay-sachs disease

Answer






This is a typical presentation of Lesch-Nyhan syndrome which is caused by deficiency hypoxanthine-guanine phosphoribosyltransferase (HGPRT) deficiency. Elevated serum and urine uric acid concentration accompanied by self-mutilating behaviors is diagnostic.

The correct answer is C