The relationship between Y chromosome DNA haplotypes and Y chromosome deletions leading to male infertility

Microdeletions on the short arm of the Y chromosome have defined three non- overlapping regions (AZFa, b, c) recurrently deleted among infertile males. These regions contain several genes or gene families involved in male germ -cell development and maintenance. Even though a meiotic origin for these m icrodeletions is assumed, the mechanisms and causes leading to microdeletio n formation are largely unknown. In order to assess whether some Y chromoso me groups (or haplogroups) are predisposed to, or protected against, deleti on formation during male meiosis, we have defined and compared Y chromosome haplogroup distribution in a group of infertile/subfertile males harbourin g Yq deletions and in a relevant Northwestern European control population. Our analyses suggest that Y chromosome deletion formation is, at least in t he study populations, a stochastic event independent of the Y chromosome ba ckground on which they arise and may be caused by other genetic and/or envi ronmental factors.