Maternal Genetic Variants Linked to Aneuploid Conception Identified in Review

Unraveling the Genetic Roots of Aneuploid Conception

Aneuploidy, an abnormal chromosome count, is a primary driver of infertility, accounting for about half of all spontaneous pregnancy losses and causing congenital disorders like Down's syndrome [1, 2, 3]. While advanced maternal age is a well-known risk factor, significant variation in aneuploidy rates among younger women suggests a strong underlying genetic component [1, 4]. Current diagnostic tools, including karyotyping and preimplantation genetic testing, often leave cases of recurrent loss unexplained [5, 6, 7, 8, 9]. A recent systematic review now synthesizes the evidence on specific maternal genetic variants that may predispose women to aneuploid conceptions, offering a potential new dimension for diagnosis and counseling [10].

Understanding Aneuploidy's Clinical Impact and Genetic Basis

Human aneuploid conception presents a substantial clinical burden as a leading cause of infertility, pregnancy loss, and congenital disorders. These chromosomal errors typically originate from faulty chromosome segregation during either oocyte meiosis or the initial mitotic divisions of the embryo. Although advanced maternal age is a well-established risk factor, it does not fully account for the observed incidence of aneuploidy, particularly the significant inter-individual variation seen among younger women. This variability points toward a substantial role for heritable maternal genetic determinants. Identifying these underlying genetic factors is critical for advancing diagnostic and prognostic capabilities, especially for patients with unexplained infertility or recurrent pregnancy loss whose reproductive challenges are not fully clarified by current clinical evaluations.

Rigorous Search and Data Extraction Methodology

To build a comprehensive evidence base, investigators conducted a systematic search of PubMed, Embase, and the Cochrane Library for studies published up to January 12, 2026. The review's pre-registered protocol (PROSPERO: CRD42025636217) ensured a transparent and rigorous methodology. Inclusion criteria were strict, limited to human studies with genetic confirmation of aneuploidy in oocytes, embryos, or fetal tissue that identified maternal variants such as rare single-nucleotide variations, single-nucleotide polymorphisms, or small insertions and deletions (≤50 bp). The search deliberately excluded non-human studies, those focused on paternal factors, and reports on structural chromosomal abnormalities to maintain a sharp focus on maternal genetics and aneuploidy. From the qualifying studies, the researchers extracted detailed data on population characteristics, variant specifics, clinical phenotypes, and the type and origin of the aneuploidy. To assess the clinical relevance of the findings, they classified rare variants using the established American College of Medical Genetics and Genomics and the Association for Molecular Pathology (ACMG/AMP) guidelines, the standard for determining a variant's pathogenicity. The quality of each included study was formally appraised using a modified Newcastle-Ottawa Scale, a tool designed to evaluate the risk of bias in observational research.

Key Maternal Genetic Variants Identified

The analysis of 28 studies revealed a set of maternal genetic variants associated with a wide spectrum of aneuploid pregnancy outcomes, including embryo arrest, implantation failure, pregnancy loss, and fetal aneuploidy. These variants were functionally grouped into four key biological pathways essential for early development: meiotic recombination (the shuffling of genetic material in oocytes), spindle dynamics (the cellular machinery that separates chromosomes), checkpoint enforcement (the quality-control system that halts cell division if errors occur), and the maternal-to-zygotic transition (the critical handover of cellular control from the mother's genes to the embryo's). Among the findings, the review identified likely pathogenic rare variants in the genes KIF18A, ELL3, and CEP120 supported by high-quality evidence. In addition, common variants in PLK4 and CCDC66 showed a robust association with aneuploid conceptions. The authors noted that while several other genes (HFM1, MCM9, MEI1, BUB1B, NLRP2, NLRP7, and TLE6) are already included on some commercial next-generation sequencing (NGS) panels for infertility, their direct causal link to aneuploidy requires further validation before they can be confidently used for this specific diagnostic purpose.

Refining Infertility Diagnosis: The 'Aneuploidy Predisposition' Framework

Based on these findings, the review proposes a more mechanism-driven approach to the genetic diagnosis of infertility, centered on the concept of 'aneuploidy predisposition'. This framework suggests that clinicians should consider an underlying genetic susceptibility to aneuploidy as a distinct diagnostic entity, complementing existing phenotype-based evaluations. Such a perspective would be most valuable for women with unexplained infertility and a normal karyotype who experience recurrent aneuploidy or show inconsistent reproductive outcomes across different cycles. For this population, identifying a genetic predisposition could offer a definitive explanation and guide future management strategies. Adopting this framework would refine clinical genetic testing paradigms and points toward future research priorities. The authors advocate for artificial intelligence-enhanced studies to better integrate complex clinical and genomic data. They also highlight the need to develop polygenic risk models, which are statistical tools that assess the cumulative impact of many small-effect genetic variants, to create a more comprehensive and personalized risk assessment for aneuploid conceptions when combined with clinical factors.

References

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