Mammalian male meiosis requires homologous recombination between the X and Y chromosomes. In humans, such recombination occurs exclusively in the short arm pseudoautosomal region (PAR1) of 2.699 Mb in size. Although it is known that complete deletion of PAR1 causes spermatogenic arrest, no studies have addressed to what extent male meiosis tolerates PAR1 size reduction. Here, we report two families in which PAR1 partial deletions were transmitted from fathers to their offspring. Cytogenetic analyses revealed that a ∼400 kb segment at the centromeric end of PAR1, which accounts for only 14.8% of normal PAR1 and 0.26% and 0.68% of the X and Y chromosomes respectively, is sufficient to mediate sex chromosomal recombination during spermatogenesis. These results highlight the extreme recombinogenic activity of human PAR1. Our data, in conjunction with previous findings, indicate that the minimal size requirement of mammalian PARs to maintain male fertility is fairly small.

中文翻译：

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人类精子发生耐受假常染色体区域的大量缩小。

哺乳动物雄性减数分裂需要 X 和 Y 染色体之间的同源重组。在人类中，这种重组仅发生在 2.699 Mb 的短臂假常染色体区域 (PAR1)。尽管已知完全删除 PAR1 会导致生精停滞，但没有研究说明雄性减数分裂在多大程度上容忍 PAR1 大小减少。在这里，我们报告了两个家庭，其中 PAR1 部分缺失从父亲传给了他们的后代。细胞遗传学分析表明，PAR1 着丝粒末端的~400 kb 片段仅占正常 PAR1 的 14.8% 和 X 和 Y 染色体的 0.26% 和 0.68%，足以在精子发生过程中介导性染色体重组。这些结果突出了人类 PAR1 的极端重组活性。我们的数据，