Impact of male age on paternal aneuploidy: single-nucleotide polymorphism microarray outcomes following blastocyst biopsy.

RESEARCH QUESTION: Does advanced paternal age (APA; ≥40 years) contribute to a higher incidence of paternal origin aneuploidy in preimplantation embryos? DESIGN: This was a multicentre retrospective study of single-nucleotide polymorphism (SNP) microarray (Natera and Karyomapping) preimplantation genetic testing (PGT) outcomes of blastocyst-stage embryos. Whole-chromosome aneuploidy analysis was performed on 2409 embryos from 389 male patients undertaking 681 assisted reproductive technology (ART) cycles between 2012-2021. Segmental aneuploidy analysis was performed on 867 embryos from 140 men undertaking 242 ART cycles between 2016-2021. Embryos were grouped based on paternal age at sperm collection: <35, 35-39 and ≥40 years. Paternal and maternal origin aneuploidy rates were compared between groups using chi-squared and/or Fisher's exact tests. RESULTS: There was no significant difference across groups in paternal origin whole-chromosome aneuploidy rate, overall (P=0.7561) or when segregated by type (trisomy and monosomy: P=0.2235 and 0.8156) or complexity (single versus 2, 3 or ≥4 aneuploidies: P=0.9733, 0.7517, 0.669 and 0.1481). Conversely, maternal origin whole-chromosome aneuploidy rate differed across groups (P<0.0001) in alignment with differing mean maternal age (P<0.001). Paternal origin deletions were 2.9-fold higher than maternal origin deletions (P=0.0084), independent of age stratification. No significant difference in paternal origin deletions was observed with APA ≥40 compared with the younger age groups (4.8% versus 2.5% and 2.8%, P=0.5292). Individual chromosome aneuploidy rates were too low to perform statistical comparisons. CONCLUSIONS: No significant association was found between APA and the incidence of paternal origin aneuploidy in preimplantation embryos, irrespective of type or complexity. Thus, APA may not be an indication for PGT.

Pre-Implantation Genetic Screening Techniques: Implications for Clinical Prenatal Diagnosis.

Chromosomal aneuploidy is responsible for a significant proportion of pregnancy failures, whether conceived naturally or through in vitro fertilization (IVF). In an effort to improve the success rate of IVF, screening embryos for aneuploidy - or pre-implantation genetic screening (PGS) - has been proposed as a means of ensuring only euploid embryos are selected for transfer. Early PGS approaches were based on fluorescence in situ hybridization testing, and have been shown not to improve live birth rates. Recent developments in genetic testing technologies - such as next-generation sequencing and quantitative polymerase chain reaction, coupled with embryo biopsy at the blastocyst stage - have shown promise in improving IVF outcomes, but they remain to be validated in adequately powered, prospective randomized trials. The extent to which IVF with PGS lowers the a priori risk of aneuploidy in ongoing pregnancies so conceived has been poorly described, rendering it difficult to incorporate the potential benefit of PGS into existing prenatal aneuploidy screening regimens such as cell-free DNA testing or conventional combined nuchal translucency and maternal biochemistry assessment. Further data on the sensitivity and specificity of various forms of molecular PGS testing would improve our understanding of the effectiveness and accuracy of these technologies. This, in addition to further research into methods of risk combination and assessment, would allow us to help our patients make better- informed decisions about whether or not to proceed with invasive diagnostic tests.