Dihydropyrimidinase (DHP) was the second enzyme in the pyrimidine degradation pathway, which catalyzed the ring-opening of 5,6-dihydrouracil and 5,6-dihydrothymine to N-carbamoyl-β-alanine and N-carbamoyl-β-aminobutyric acid, respectively 2 patients with complete DHP deficiency were reported, both of whom were heterozygotes with missense mutation 1078T>C(W360R) in exon 6 and new missense mutation 1235G>T(R412M) in exon 7.[15] Our DEG analysis revealed that DPYS is down-regulated in TS patients, resulting in lower alanine levels than normal people. The gene discussed is DPYS; the disease is hyperinsulinemic hypoglycemia, familial, 4.