Investigating the relation between chromosomal polymorphism and recurrent pregnancy loss: A cohort study

Abstract

Chromosomal polymorphisms (CPM) are minor variation of karyotype, found in >1% of the general population. Heterochromatin, the inactive part of the chromosome, shows frequent polymorphism - increase/decrease in length. Recently, studies show that heterochromatin is not inert, but contains genes essential for spindle attachment, chromosome movement, meiotic pairing, and sister chromatid cohesion. Balanced translocation in parents, reciprocal and robertsonian, can disrupt important genes, and produce gametes with unbalanced gene dosage, causing spontaneous miscarriage. To correlate between chromosomal polymorphisms/ structural alterations and first trimester Recurrent Pregnancy Loss (RPL) primary infertility. : 100 couples with primary infertility or RPLs, were karyotyped by 72-h whole blood culture. Giemsa banding (GTG) was done in all cases. 20 metaphases were analysed according to the ISCN criteria. The total no. of RPLs was noted for each couple with abnormal karyotype. Of the 44 couples with abnormal karyotype, 36 (82%) had chromosomal polymorphism, 7 (16%) showed structural abnormality and 1 (2%) had numerical abnormality. Chromosome 9qh+ was present in the majority (33.33%). Among the D, G chromosomes, chromosome 15ps+/pstk+ were found in 22.22% but average no. of RPL was 2.15, whereas average RPL in Chr.22ps+ (incidence 5.55%.) was 3 (highest). Among male partners, Chr.Yqh+/Yqh- were found in 12 (33.33%) couples. Among the structural abnormalities (16%), balanced translocation accounted for 11.36%, maximum of which were Reciprocal translocations. The frequency of chromosomal abnormalities is higher among couples with RPLs and infertility, compared to the general population. Karyotyping gives important genetic information, thus acting as a good diagnostic tool, and helps to plan ART or perform prenatal testing.