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

BACKGROUND: 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.