Combined 17 alpha-hydroxylase/17,20-lyase deficiency due to a 7-basepair duplication in the N-terminal region of the cytochrome P45017 alpha (CYP17) gene

J Clin Endocrinol Metab. 1990 May;70(5):1325-9. doi: 10.1210/jcem-70-5-1325.


17 alpha-Hydroxylase deficiency is characterized by defects in either or both of the 17 alpha-hydroxylase/17,20-lyase activities. We have elucidated the molecular basis of the combined deficiency of these activities in a Japanese female who is genotypically male and the child of a consanguineous marriage. The complete exonic sequence of the patient's CYP17 (P45017 alpha) gene revealed a seven-basepair duplication (GCGCACA) in exon 2 which leads to a frame shift and, subsequently, a premature stop codon. Because this stop codon occurs N-terminal to the heme-binding sequence, the presence of this mutation leads to the absence of a functional P45017 alpha-protein in adrenal cortex and testis. This, in turn, leads to an absence of sex steroids and excessive secretion of steroids with mineralocorticoid activity and, consequently, female external genitalia and hypertension in this 46XY patient.

Publication types

  • Case Reports
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Adolescent
  • Adrenal Hyperplasia, Congenital / enzymology*
  • Adrenal Hyperplasia, Congenital / genetics*
  • Aldehyde-Lyases / deficiency
  • Aldehyde-Lyases / genetics*
  • Amino Acid Sequence
  • Base Sequence
  • Blotting, Southern
  • Cytochrome P-450 Enzyme System / deficiency
  • Cytochrome P-450 Enzyme System / genetics*
  • DNA Mutational Analysis
  • Exons
  • Female
  • Gene Expression Regulation, Enzymologic*
  • Genotype
  • Humans
  • Molecular Sequence Data
  • Multigene Family*
  • Steroid 17-alpha-Hydroxylase / genetics*
  • Steroid Hydroxylases / genetics*


  • Cytochrome P-450 Enzyme System
  • Steroid Hydroxylases
  • Steroid 17-alpha-Hydroxylase
  • Aldehyde-Lyases