title: [Genetic analysis of gonadotropin-gonadal axis in boys: a twin study].
abstract: OBJECTIVE
  To analyse the heritabilities of serum luteinizing hormone(LH), follicle-stimulating hormone (FSH), testosterone (T) and estradiol (E2) in twin boys, and to study the genetic contributions to gonadotropin-gonadal axis.
  
  
  METHODS
  A total of 51 pairs of male twins, 35 monozygotic (MZ) and 16 dizygotic(DZ) aged 5 to 11 years, were investigated. Serum gonadotropin and sex hormone were measured by radioimmunoassay. The twin zygosity was verified by determination of short tandem repeat amplified fragment length polymorphism systems. The genetic analysis was performed using intraclass correlation coefficient method.
  
  
  RESULTS
  The intraclass correlation coefficient was greater in the MZ twins than in the DZ twins. The estimated heritabilities were respectively LH 0.51, FSH 0.32, T 0.81, E2 0.41.
  
  
  CONCLUSIONS
  Genetic factors are major determinants of gonadotropin-gonadal axis in boys.
authors.affiliation: Institute of Child and Adolescent Health, Peking University, Beijng 100083, China. wangvei@eyou.com
authors.forename: Wei
authors.initials: W
authors.lastname: Wang
authors.forename: Chengye
authors.initials: C
authors.lastname: Ji
authors.forename: Zengchang
authors.initials: Z
authors.lastname: Peng
authors.forename: Yepeng
authors.initials: Y
authors.lastname: Yang
authors.forename: Tianjiao
authors.initials: T
authors.lastname: Chen
authors.forename: Hongjuan
authors.initials: H
authors.lastname: Li
authors.forename: Xiaohai
authors.initials: X
authors.lastname: Zhan
authors.forename: Ying
authors.initials: Y
authors.lastname: Wang
authors.forename: Yonghua
authors.initials: Y
authors.lastname: Hu
mesh_terms: D002648:Child; D002675:Child, Preschool; D012739:Gonadal Steroid Hormones / Q000097:blood*; D006062:Gonadotropins / Q000097:blood*; D006801:Humans; D008297:Male; D011863:Radioimmunoassay
chemical_list: D012739:Gonadal Steroid Hormones; D006062:Gonadotropins