CYP19A1 and hyperinsulinemic hypoglycemia, familial, 4: We are reporting a case of aromatase deficiency presented with atypical genitalia and maternal virilization due to a novel mutation in <i>CYP19A1</i>.<h4>Case presentation</h4>A 10-day-old newborn presented with atypical genitalia and a history of maternal virilization during pregnancy.