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- Title
Partial deficiency of 17γ-hydroxylase/17,20-lyase caused by a novel missense mutation in the canonical cytochrome heme-interacting motif.
- Authors
Rubtsov, Petr; Nizhnik, Alexander; Dedov, Ivan; Kalinchenko, Natalia; Petrov, Vasily; Orekhova, Anna; Spirin, Pavel; Prassolov, Vladimir; Tiulpakov, Anatoly
- Abstract
Background Deficiency of 17γ-hydroxylase/17,20-lyase is a rare cause of 46,XY disordered sex development. Objective We characterize in vitro and in vivo effects of two novel CYP17A1 gene mutations identified in a patient with a mild phenotype of CYP17A1 deficiency. Subjects and methods A 46,XY patient presented with ambiguous genitalia. CYP17A1 deficiency was suspected at 2 months on the basis of steroid analysis performed by liquid chromatographyâ€"tandem mass spectrometry (LCâ€"MS/MS). Mutational analysis of the CYP17A1 gene was performed by PCR and Sanger sequencing. To characterize the effect of CYP17A1 mutation on 17γ-hydroxylase and 17,20-lyase activities in vitro, HEK293 cells were transiently transfected with CYP17A1 expression plasmids, incubated with progesterone or 17-OH-pregnenolone and concentrations of 17-OH-progesterone or DHEA were then measured in the cell culture medium by LCâ€"MS/MS. Results: Clinical and hormonal findings in the patient were consistent with partial combined deficiency of 17γ-hydroxylase/17,20-lyase. The sequencing of the CYP17A1 gene in the patient revealed compound heterozygosity for two novel mutations: c.107delT p.R36fsX107 and p.W121R. After 6-h in vitro culture of transfected HEK293 cells in the presence of 1 μM progesterone, 17γ-hydroxylase activity of p.W121R mutant was 60.5±16.3%, while 17,20-lyase activity of mutant measured from the amount of DHEA produced in the presence of 1 μM of 17-OH-pregnenolone was 15.8±2.6% compared with the WT. Conclusions p.W121R substitution, affecting the first residue in the conserved heme-interacting WXXXR motif of CYP17A1, is associated with partial combined deficiency of 17γ-hydroxylase/17,20-lyase.
- Subjects
SEX differentiation disorders; MISSENSE mutation; FERROCYTOCHROMES; HYDROXYLASES; LYASES; TANDEM mass spectrometry; PROGESTERONE; STEROID synthesis
- Publication
European Journal of Endocrinology, 2015, Vol 172, Issue 5, pK19
- ISSN
0804-4643
- Publication type
Article
- DOI
10.1530/EJE-14-0834