A Novel CYP21A2 Gene Mutation in Classic Congenital Adrenal Hyperplasia.

A 3-month-old boy presented with failure to thrive since birth, and poor feeding, lethargy and vomiting for one month. He was born to consanguineous parents and weighed 3.0 kg at birth. There was no family history of previous similarly affected member or early deaths. On examination, his weight and length were 3.25 kg (-4.5 Zscore) and 57.0 cm (-1.35 Z-score), respectively. Genital hyperpigmentation was noted, but there was no ambiguity. Laboratory investigations showed low serum sodium (126 mEq/L), high serum potassium (6.7 mEq/L), and low blood pH (7.09). The 17-hydroxytprogesterone (17-OHP) level was 38.7 ng/mL. Ultrasonography showed enlarged adrenals. A diagnosis of classic Congenital adrenal hyperplasia (CAH) due to 21hydroxylase (21-OH) deficiency was considered and replacement steroid therapy was initiated. Synacthen test was performed in follow-up after withholding steroids. The baseline serum cortisol and 17-OHP values were 4.60 nmol/L and 22.4 ng/mL and peak stimulated values were 4.87 nmol/L and 54.7 ng/mL, respectively.