Q. A 2-week-old female infant was referred to the clinic for evaluation of vomiting, failure to thrive, and ambiguous genitalia. The parents noted that the infant had a larger than normal clitoris and a labial fusion. Upon examination, the infant was found to have a weight of 4.0 kg (10th percentile) and a length of 55 cm (50th percentile). Blood pressure was 60/30 mmHg. The infant was born full-term via vaginal delivery with a birth weight of 3.8 kg. There is no significant family history of endocrine disorders. The infant has ambiguous genitalia with a larger than normal clitoris and labial fusion. There was evidence of virilization. Initial laboratory studies showed elevated serum 17-hydroxyprogesterone levels and decreased serum cortisol, aldosterone, and 11-deoxycorticosterone levels. Sodium levels are decreased whereas there is a high level of potassium. What is the most likely diagnosis?