CYP17A1 and hyperinsulinemic hypoglycemia, familial, 4: Compared to the ratios we have obtained from patients with classical 17OHD or partial combined 17α-hydroxylase/17,20-lyase deficiency (cases 5 and 6), their corticosterone/cortisol metabolite ratios are lower, suggesting higher residual in vivo CYP17A1 17α-hydroxylase activity in milder cases.