Influence of female karyotype polymorphic variants on oocyte quality and embryo development

Study question Do polymorphic variants in the karyotype of women undergoing an IVF cycle directly affect oocyte and embryo laboratory parameters? Summary answer The presence of certain polymorphic variants negatively affects the oocyte survival rate and the blastocyst quality in an IVF cycle. What is known already In the recent years, there has been a growing interest in the study of polymorphic variants in infertile patients because their incidence, compared to the fertile population, is increased. However, most research has focused on the male patient study. Several studies have reported information about clinical outcomes, but the influence they may have on IVF laboratory procedures and embryo development has rarely been studied up to the blastocyst stage. In addition, it is very rare to find publications that show the study of polymorphisms according to their type or combination. Study design, size, duration Retrospective evaluation of a cohort of women who underwent autologous IVF cycles and karyotyping. The sample included 424 IVF cycles performed between July 2017-December 2021: control group (CG) with normal karyotype (211) and study group (SG) with polymorphisms (213). We studied the correlation between karyotype polymorphisms and laboratory outcomes in terms of: Number of Oocytes Retrieved, Fresh Oocyte Maturity (MII), Oocyte Survival after Thawing (TS), Fertilization (FZ), Oocyte Degeneration (OD) and Non-viable embryo rates. Participants/materials, setting, methods Analysis of the women karyotype, prior to the IVF cycle, was performed using the guidelines of the International System for Human Cytogenetic Nomenclature (ISCN). Differences between the different study groups (presence or absence of different chromosomal polymorphisms) were assessed with the appropriate statistical test according to the normality or non-normality of the variable distribution. Statistical analysis was performed using R statistical software (v.4.2.0) and SPSS (v.23.0, Chicago, IL, USA). Main results and the role of chance Average female age was 37.72 ± 3.98 (CG) and 36.73 ± 3.59 (SG). Average number of mature oocytes (MII) was: 6.45 ± 4.96(CG) and 7.59 ± 5.10 (SG). Statistically significant differences were found regarding the number of oocytes retrieved between the CG (8.14 ± 5.90) and the SG (9.53 ± 6.63) (p = 0.036), increasing when the ps+ variant was present (9.75 ± 7.21) (p = 0.045). However, no statistically significant differences were found between the presence of polymorphism (SG) and the CG in terms of: number of MII: 79.85% vs. 80.48% (p = 0.447), FZ: 73.76% vs. 70.49% (p = 0.352) and OD: 8.76% vs. 8.36% (p = 0.563) rates. In addition, the TS rate was statistically significant when there was the ps+ variant (82.95%) (p = 0.010) and/or combinations of more than one polymorphic variant (87.80%) (p = 0.044), compared to the CG (93.51%). Finally, according to embryo quality there was an increase in the non-viable embryos rate, on day 5 and/or day 6 of development, between the CG (34.17%) and the SG (43.02%) (p < 0.001), increasing when the ps+ variable was present (45.57%) (p < 0.001) and/or combinations of more than one polymorphic variant (p = 0.045). The results were corrected for confounding variables such as maternal age, oocyte origin and male factor variables, including polymorphic variants in the male karyotype. Limitations, reasons for caution Other variables that have not been analyzed may influence the outcomes. Larger prospective studies including homogeneous cohorts are needed in order to corroborate our initial results. Wider implications of the findings The polymorphic variants in the female karyotype, especially the “ps+” variant and the combination of multiple variants, could influence certain parameters in the laboratory. Therefore, it is important to request a karyotype to all patients before starting IVF treatment. Trial registration number NOT APPLICABLE