Parental chromosomal heteromorphisms are not associated with an increased risk of embryo aneuploidy

Abstract

Objective: Although chromosomal heteromorphisms are commonly found in the general population, some researchers have suggested a correlation with higher rates of embryo aneuploidy. This study aimed to assess the rates of embryo aneuploidy in couples who carry a chromosome heteromorphism.Methods: The study included couples who had G-banding karyotype testing and underwent an IVF/ PGT-A cycle between January 2012 and March 2018. The participants were classified by couple karyotype: Group A: ≥1 patient reported to be a heterochromatic variant carrier; Group B: both partners reported to be "normal". We assessed the rates of aneuploidy among the groups. We ran a multivariate regression analysis to assess the relationship between heterochromatic variants and the rates of embryo aneuploidy.Results: Of the 946 couples analyzed, 48 (5.0%) reported being a carrier of ≥1 heterochromatic variant. We had 869 IVF/PGT-A cycles included in the analysis (Group A: n=48; Group B: n=82). There were no significant differences in embryo ploidy rates among the groups. The heterochromatic chromosome variant was not associated with increased likelihoods of aneuploidy (OR=1.04, CI:95% 0.85-1.07; p=0.46). Finally, the gender of the heterochromatic variant carrier had no association with increased likelihood of aneuploidy (OR 1.02, CI 95% 0.81-1.28, p=0.82).Conclusions: Our study showed no association between parental heterochromatic chromosome variants and subsequent embryo aneuploidy rates. Ploidy rates do not appear to be negatively associated with couples when at least one patient is reported to be a carrier of a heterochromatic variant on the karyotype.

Evaluation of nanopore sequencing on polar bodies for routine pre-implantation genetic testing for aneuploidy

“…The GC-richest chromosomes 16, 17, 19 and 22 often display increased levels of noise. Also chromosomes with heterochromatic polymorphisms, like chromosomes 1, 9 and 16 differ due to normal, benign variations in heterochromatin-content, which can be visualized by microscopy but is hard to interpret in sequencing-based methods or aCGH (Hernandez-Nieto et al, 2021). In our study, the chromosomes 9, 19, 21 and 22 showed most discordances (Figure 3).…”