title: Androgen receptor CAG repeat length is associated with body fat and serum SHBG in boys: a prospective cohort study.
abstract: BACKGROUND
  Longer androgen receptor gene CAG trinucleotide repeats, AR (CAG)n, have been associated with reduced sensitivity of the androgen receptor (AR) in vitro as well as in humans. Furthermore, short AR (CAG)n have been associated with premature adrenarche.
  
  
  OBJECTIVE
  The aim of the study was to evaluate associations between the AR (CAG)n polymorphism and development of pubic hair, levels of androgens, and body fat content in healthy boys.
  
  
  METHODS
  A longitudinal study of 78 healthy boys (age 6.2-12.4 years at inclusion) from the COPENHAGEN Puberty Study was conducted with clinical examinations and blood samples drawn every 6 months. The AR (CAG)n length was established by direct DNA sequencing and reproductive hormones were measured in serum by standardized analyses.
  
  
  RESULTS
  Median AR (CAG)n length was 22 (range, 17-30). Before puberty (at 10 years of age), boys with long CAG repeats (CAG ≥ 24) had lower levels of SHBG (88 vs 125 nmol/L) (P < .05) and a nonsignificant trend toward higher median skinfold thickness (41 vs 31 mm) (P = .06) compared with boys with an average number of CAG repeats (CAG 21-23). In contrast, the inverse association was observed at puberty (at 12 years of age) in boys with short CAG repeats (CAG 17-20) (P < .05). Serum levels of LH and testosterone (at 12 years) were significantly higher in boys with long CAG repeats compared with boys with an average number of CAG repeats (P = .05).
  
  
  CONCLUSIONS
  The observed associations between AR (CAG)n and peripubertal fat accumulation and serum SHBG concentrations indicate that this genetic polymorphism may influence the androgen-dependent fine-tuning of metabolic and reproductive factors at a young age.
authors: Department of Growth and Reproduction, Rigshospitalet, Faculty of Health Sciences, University of Copenhagen, 2100 Copenhagen, Denmark. annette.mouritsen@rh.regionh.dk
authors: Annette
authors: A
authors: Mouritsen
authors: Casper P
authors: CP
authors: Hagen
authors: Kaspar
authors: K
authors: Sørensen
authors: Lise
authors: L
authors: Aksglaede
authors: Mikkel G
authors: MG
authors: Mieritz
authors: Katharina M
authors: KM
authors: Main
authors: Kristian
authors: K
authors: Almstrup
authors: Ewa
authors: E
authors: Rajpert-De Meyts
authors: Anders
authors: A
authors: Juul
mesh_terms: D000273:Adipose Tissue / Q000502:physiology*; D000735:Androstenedione / Q000097:blood; D002648:Child; D019314:Dehydroepiandrosterone Sulfate / Q000097:blood; D003718:Denmark; D006801:Humans; D008137:Longitudinal Studies; D007986:Luteinizing Hormone / Q000097:blood; D008297:Male; D011446:Prospective Studies; D011627:Puberty / Q000097:blood / Q000235:genetics*; D011944:Receptors, Androgen / Q000235:genetics*; D012738:Sex Hormone-Binding Globulin / Q000378:metabolism*; D013739:Testosterone / Q000097:blood; D018911:Trinucleotide Repeats / Q000235:genetics*
chemical_list: D011944:Receptors, Androgen; D012738:Sex Hormone-Binding Globulin; D013739:Testosterone; D000735:Androstenedione; D019314:Dehydroepiandrosterone Sulfate; D007986:Luteinizing Hormone