Aneuploidy across individual chromosomes at the embryonic level in trophectoderm biopsies: changes with patient age and chromosome structure.

Purpose: To characterize each chromosome's risk for being involved in embryonic aneuploidy.

Methods: This is a retrospective cohort study conducted at a single, academic center. The cohort consisted of 15,169 consecutive trophectoderm biopsies which then underwent comprehensive chromosome screening utilizing validated real-time polymerase chain reaction (RT-PCR) or single nucleotide polymosphism (SNP) array platforms. Analysis was done to determine probability of aneuploidy by chromosome, changes in that risk with increasing maternal age, and in relationship of aneuploidy to chromosomal structure as classified by prior cytogenetic literature.

Results: The highest prevalence of imbalances leading to aneuploidy was seen for chromosomes 13, 15, 16, 18, 19, 21, and 22. While elevated in all age groups, there was a disproportionate rise in aneuploidy rates for these chromosomes with increasing maternal age. When classic cytogenetic karyotype groups were compared, the overall smaller groups D, E, and G were associated with the highest rates. Similarly, when grouped based upon structure, acrocentric chromosomes exhibited the highest rates of aneuploidy, followed by the metacentric chromosomes, with the lowest prevalence of error in those with submetacentric structures.

Conclusions: The highest rates of chromosomal aneuploidy were found in chromosomes known to be involved in clinically detectable, abnormal pregnancies, not just simply implantation failure. The rate of aneuploidy in these chromosomes rises disproportionately with age when compared to the other chromosomes which may provide information about chromosomal susceptibility to aging. The biological structure groupings did show varied aneuploidy rates which may provide insight into the biology of aneuploidy.