17α-hydroxylase/17,20 carbon chain lyase deficiency caused by p.Tyr329fs homozygous mutation:Three case reports

p.Tyr329fs is a cytochrome P450c17 mutation among Chinese individuals.However,data on 17-α-hydroxylase deficiency caused by cytochrome P450c17 p.Tyr329fs homozygous mutation are lacking.This paper is a case report of three patients homozygous for p.Tyr329fs who were diagnosed with 17-α-hydroxylase deficiency between 2005 and 2019.CASE SUMMARY Case 1 presented with hypertension,hypokalemia,sexual infantilism and delayed bone age.The patient had a 46,XY karyotype,was homozygous for p.Tyr329fs and was recently treated with dexamethasone 0.375 mg qn.Case 2 presented with hypokalemia,sexual infantilism,osteoporosis and delayed bone age.The patient had a 46,XY karyotype,was homozygous for p.Tyr329fs and was treated with dexamethasone 0.75 mg qn at the last follow-up.Serum potassium and blood pressure could be maintained within normal range for cases 1 and 2.Case 3 presented with amenorrhea,sexual infantilism,osteopenia and delayed bone age.The patient had a 46,XX karyotype,was homozygous for p.Tyr329fs and was treated with dexamethasone 0.75 mg qn and progynova 1 mg qd.Outpatient follow-up revealed an adrenocorticotropic hormone(8 AM)of<5.00 pg/mL.CONCLUSION The homozygous p.Tyr329fs mutation usually manifests as a combined deficiency,and definitive diagnosis depends primarily on genetic testing.