Lack of association between Y chromosome haplogroups and male infertility in Japanese men

The Y chromosome carries several genes involved in spermatogenesis, which are distributed in three regions in the euchromatic part of the long arm, called AZFa (azoospermia factor a), AZFb, and AZFc. Microdeletions in these regions have been seen in 10-15% of sterile males with azoospermia or severe oligozoospermia. The relatively high de novo occurrence of these microdeletion events might be due to particular chromosome arrangements associated with certain Y chromosome haplogroups. To test whether there is any association between Y chromosome types and male infertility, we studied a sample of 84 Japanese oligozoospermic or azoospermic males. The patients were analyzed for the presence of Yq microdeletions and also typed with a battery of unique event polymorphisms (UEPs) to define their Y haplogroups. Six of the infertile patients presented likely pathological microdeletions detectable with the sequence tagged sites (STS) markers used. There was no significant association between Y chromosome haplogroups and the microdeletions. We also compared the Y haplogroup frequencies in our subset sample of 51 idiopathic azoospermia patients with 57 fertile control Japanese males, and did not observe any significant differences. Contrary to previous reports, our data suggest that Y microdeletions and other molecular events causally associated with male infertility in Japan occur independently of the Y chromosome background.