title: Y chromosome gr/gr deletions are a risk factor for low semen quality.
abstract: BACKGROUND
  Subfertility affects one in eight couples. In up to 50% of cases, the male partner has low semen quality. Four Y chromosome deletions, i.e. Azoospermia factor a (AZFa), P5/proximal-P1 (AZFb), P5/distal-P1 and AZFc deletions, are established causes of low semen quality. Whether a recently identified partial AZFc deletion, the gr/gr deletion, also causes low semen quality is at present unclear.
  
  
  METHODS
  We used a dual approach to review the effect of the gr/gr deletion on semen quality. First, we conducted a systematic review and meta-analysis of previous association studies, to compare the prevalence of gr/gr deletions between azoo-/oligozoospermic men and normozoospermic men. Secondly, we studied a cohort of 1041 male partners of subfertile couples unselected for semen quality. We employed a cross-sectional design by screening all men for the gr/gr deletion and comparing the semen quality of men with and without the gr/gr deletion.
  
  
  RESULTS
  Seven studies were included in the meta-analysis. The gr/gr deletion was significantly more prevalent among azoo-/oligozoospermic men than among normozoospermic men (OR 2.4, 95% CI 1.75-3.30). In our cohort, 25 men carried a gr/gr deletion. Men with this genotype had a lower sperm concentration (median 34 x 10(6)/ml versus 53 x 10(6)/ml, P = 0.017), total sperm count (median 108 x 10(6) versus 152 x 10(6), P = 0.006) and total motile sperm count (median 20 x 10(6) versus 50 x 10(6), P = 0.010) than men without the gr/gr deletion.
  
  
  CONCLUSIONS
  Y chromosome gr/gr deletions significantly reduce sperm counts and are thus associated with low semen quality.
authors: Centre for Reproductive Medicine, Department of Obstetrics and Gynecology, Academic Medical Centre, University of Amsterdam, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands.
authors: L
authors: L
authors: Visser
authors: G H
authors: GH
authors: Westerveld
authors: C M
authors: CM
authors: Korver
authors: S K M
authors: SK
authors: van Daalen
authors: S E
authors: SE
authors: Hovingh
authors: S
authors: S
authors: Rozen
authors: F
authors: F
authors: van der Veen
authors: S
authors: S
authors: Repping
mesh_terms: D000328:Adult; D053713:Azoospermia / Q000235:genetics; D041322:Chromosomes, Human, Y / Q000235:genetics*; D015331:Cohort Studies; D006801:Humans; D008297:Male; D009845:Oligospermia / Q000235:genetics; D012307:Risk Factors; D012661:Semen / Q000502:physiology*; D055101:Semen Analysis; D017384:Sequence Deletion