The impact of androgen receptor polymorphism and parental ethnicity on semen quality in young men from Latvia

Recent studies on young men from the general population have demonstrated geographic and ethnic differences in semen quality. The aim of this study was to investigate whether reported ethnic differences in semen quality might be associated with the maternally derived CAG and GGN polymorphisms in the androgen receptor gene or paternal ethnicity. In total 114 military conscripts from Latvia were included in the study. Information on maternal and parental ethnicity was collected by questionnaires. CAG and GGN repeats were analysed by direct sequencing of leukocyte DNA. Men with Latvian mothers (n = 83) had marginally shorter CAG repeat length (21.6 +/- 2.9) as compared with those with non-Latvian mothers (22.9 +/- 3.2, n = 31), not reaching statistical significance (p = 0.053). Sperm concentration did not differ significantly between these two groups (76 +/- 59 and 70 +/- 52, p = 0.9 respectively). In contrast, significantly higher sperm concentration and total sperm count were found in men with Latvian fathers (n = 77) as compared with men with non-Latvian fathers (n = 37) (80 +/- 61 vs. 62 +/- 48, p = 0.035, for sperm concentration and 225.7 +/- 209 vs. 158.4 +/- 134.4, p = 0.002, for total sperm count respectively). CAG repeat length did not correlate with any semen parameters in the whole population. However, GGN repeat length correlated with semen volume: men with GGN > 23 presented with higher semen volume (3.2 +/- 2.1) as compared with men with GGN = 23 (2.6 +/- 1.3, p = 0.04) or GGN < 23 (2.0 +/- 1.2, p = 0.006). We conclude that GGN repeat length has an impact on semen volume, whereas differences in sperm numbers are associated with the paternal ethnicity.