AKR1D1 and hyperinsulinemic hypoglycemia, familial, 4: More comprehensive GC-MS analysis performed 8 years later on this original urine sample, and only after the identification of the mutation in AKR1D1, showed that Δ4-3-oxo bile acids, while present, accounted for <2% of the total bile acids in urine, and the 5α-reduced metabolite, allo-cholic acid also synthesized in patients with Δ4-3-oxosteroid 5β-reductase deficiency was also found in traces [6], because the urine was dominated by UDCA and its metabolites (data not shown).