The unbalanced transmission of chromosomes in human gametes and early preimplantation embryos causes aneuploidy, which is a major cause of infertility and pregnancy failure.

A baseline of 20% of human oocytes are estimated to be aneuploid and this increases exponentially from the age of 35 years, reaching on average 80% by the age of 42 years. As a result, reproductive senescence in human females is predominantly determined by the accelerated decline in genetic quality of oocytes as the woman ages.

Understanding mechanisms of chromosome segregation and aneuploidies in the female germline is a crucial step towards the development of new diagnostic approaches and, possibly, for the development of therapeutic targets and molecules.

A study from the GeneraLife team, published in “Human Reproduction Update”, reviewed emerging mechanisms that may drive human aneuploidy, in particular the maternal age effect.

Advances in genomic and imaging technologies allowed unprecedented insight into chromosome segregation in human oocytes: this includes the identification of a novel chromosome segregation error, termed “reverse segregation”, that were not predicted based on murine models.

Elucidation of mechanisms that result in errors in chromosome segregation in meiosis may lead to therapeutic developments that could improve reproductive outcomes by reducing aneuploidy.

Genome-wide maps of recombination and chromosome segregation