title: CAG repeat length in the androgen receptor gene and gonadotrophin suppression influence the effectiveness of hormonal male contraception.
abstract: OBJECTIVE
  Nonuniformity in suppression of spermatogenesis induced by various hormones or hormone combinations has impeded the development of an effective hormonal male contraceptive. The basis for this heterogeneity in response remained unresolved to date; however, the presence of ethnic differences points to an involvement of genetic factors.
  
  
  METHODS
  In a retrospective analysis we investigated the impact of a CAG repeat polymorphism in the androgen receptor and polymorphic sites in the oestrogen and FSH receptor genes on spermatogenic suppression in 85 Caucasian men treated with different regimens of hormonal contraception.
  
  
  RESULTS
  Failure to reduce sperm concentrations below 3 million/ml was significantly associated with insufficient suppression of gonadotrophins. The extent of gonadotrophin suppression was not explained by any polymorphism but was primarily pharmacological, resulting from addition of gestagens to testosterone. When LH and FSH suppression was rapid and persistent none of the polymorphisms studied explained why some men failed to achieve azoospermia. In cases with incomplete gonadotrophin suppression the chances of becoming azoospermic were 2.5 times higher in men having more than 22 CAG repeats.
  
  
  CONCLUSIONS
  In summary, our analysis shows that in a subset of men, effective hormonal male contraception can be achieved even in the absence of complete gonadotrophin suppression.
authors.affiliation: Institute of Reproductive Medicine of the University, Münster, Germany.
authors.forename: Sigrid V
authors.initials: SV
authors.lastname: Eckardstein
authors.forename: Anja
authors.initials: A
authors.lastname: Schmidt
authors.forename: Axel
authors.initials: A
authors.lastname: Kamischke
authors.forename: Manuela
authors.initials: M
authors.lastname: Simoni
authors.forename: Jörg
authors.initials: J
authors.lastname: Gromoll
authors.forename: Eberhard
authors.initials: E
authors.lastname: Nieschlag
mesh_terms: D000328:Adult; D016009:Chi-Square Distribution; D003272:Contraceptive Agents, Male / Q000008:administration & dosage*; D003278:Contraceptives, Oral, Hormonal / Q000008:administration & dosage*; D003864:Depression, Chemical; D047628:Estrogen Receptor alpha; D006065:Gonadotropins, Pituitary / Q000097:blood; D006801:Humans; D008297:Male; D016017:Odds Ratio; D011110:Polymorphism, Genetic; D011944:Receptors, Androgen / Q000235:genetics*; D011960:Receptors, Estrogen / Q000235:genetics; D011962:Receptors, FSH / Q000235:genetics; D012091:Repetitive Sequences, Nucleic Acid; D012189:Retrospective Studies; D013076:Sperm Count; D013091:Spermatogenesis / Q000187:drug effects*; D018709:Statistics, Nonparametric
chemical_list: D003272:Contraceptive Agents, Male; D003278:Contraceptives, Oral, Hormonal; D047628:Estrogen Receptor alpha; D006065:Gonadotropins, Pituitary; D011944:Receptors, Androgen; D011960:Receptors, Estrogen; D011962:Receptors, FSH