[Analysis of genetic etiology and related factors in 1 065 women with spontaneous abortions].

OBJECTIVE

To explore the genetic etiology and related factors in 1 065 women with spontaneous abortions.

METHODS

All patients have presented at the Center of Prenatal Diagnosis of Nanjing Drum Tower Hospital from January 2018 to December 2021. Chorionic villi and fetal skin samples were collected, and the genomic DNA was assayed by chromosomal microarray analysis (CMA). For 10 couples with recurrent spontaneous abortions but normal CMA results for abortive tissues, non-in vitro fertilization-embryo transfer (IVF-ET) pregnancies and no previous history of live births and no structural abnormalities of the uterus, peripheral venous blood samples were collected. Genomic DNA was subjected to trio-whole exome sequencing (trio-WES). Candidate variants were verified by Sanger sequencing and bioinformatics analysis. Multifactorial unconditional logistic regression analysis was carried out to analyze the factors that may affect chromosomal abnormality in spontaneous abortions, such as the age of the couple, number of previous spontaneous abortions, IVF-ET pregnancy and history of live birth. The incidence of chromosomal aneuploidies in spontaneous abortions during the first trimester was compared in young or advanced-aged patients by chi-square test for liner trend.

RESULTS

Among the 1 065 spontaneous abortion patients, 570 cases (53.5%) of chromosomal abnormalities were detected in spontaneous abortion tissues, which included 489 cases (45.9%) of chromosomal aneuploidies and 36 cases (3.4%) of pathogenic/likely pathogenic copy number variations (CNVs). Trio-WES results have revealed one homozygote variant and one compound heterozygote variants in two pedigrees, both of which were inherited from the parents. One likely pathogenic variant was detected in the patient from two pedigrees. Multifactorial unconditional Logistic regression analysis suggested that age of patient was an independent risk factor of chromosome abnormalities (OR = 1.122, 95%CI: 1.069-1.177, P < 0.001), the number of previous abortions and IVF-ET pregnancy were independent protective factors for chromosomal abnormalities (OR = 0.791, 0.648; 95%CI: 0.682-0.916, 0.500-0.840; P = 0.002, 0.001), whilst the age of husband and history of live birth were not (P > 0.05). The incidence of aneuploidies in the abortive tissues has decreased with the number of previous spontaneous abortions in young patients (χ² = 18.051, P < 0.001), but was not significantly correlated with the number of previous spontaneous abortions in advanced-aged patients with spontaneous abortions (P > 0.05).

CONCLUSION

Chromosomal aneuploidy is the main genetic factor for spontaneous abortion, though CNVs and genetic variants may also underlie its genetic etiology. The age of patients, number of previous abortions and IVF-ET pregnancy are closely associated with chromosome abnormalities in abortive tissues.