Maternal origin of the human aneuploidies. Are homolog synapsis and recombination to blame? Notes (learned) from the underbelly.

Aneuploidy is the leading cause of mental deficiency in human newborns. Indirect studies suggest that, in most of the cases, the extra chromosome comes from an inaccurate meiotic division. But, particularly, all results seem to indicate that oogenesis is more prone to err than is spermatogenesis. Unfortunately, due to the time-frame in which meiosis takes place in the mammalian males and females, most of the studies performed so far have focused on analyzing male meiosis. Recently, some studies focusing on human meiosis have been published. Some of them revealed important sex-specific differences that may be involved in the predominant involvement of the human female in the genesis of aneuploidy. In this article, the current knowledge we have about human female meiotic synapsis and recombination is summarized and we try to relate it to the human aneuploidy origin.