Prenatal diagnosis of chromosomal polymorphisms: most commonly observed polymorphism on Chromosome 9 have associations with low PAPP-A values.

Introduction: To identify the prevalence and types of fetal chromosomal polymorphisms in pregnant women and to examine possible associations with screening test parameters. Materials and methods: Fetal chromosomal polymorphism rate was investigated in pregnant women who had been implemented for invasive prenatal test in a tertiary reference center in Thrace Region of Turkey. Fetal chromosomal polymorphisms were determined and their effects on screening tests' parameters were investigated. Possible differences in the first and second-trimester screening test parameters between women; with fetal chromosomal polymorphism who had screening test results (Group 1) and those with a normal karyotype (Group 2) were evaluated. Results: Fetal chromosomal polymorphism prevalence was 5.3% (n = 101). The most common polymorphisms were identified on chromosome 9, 1, and 16 [54.5% (n = 55); 8.9% (n = 9), and 6.9% (n = 7), respectively]. The most common polymorphic variant was 9qh+ (n = 23; 22.8%). Among the screening test parameters, significantly lower pregnancy-associated plasma protein-A (PAPP-A) (p = .028) and higher unconjugated estriol (uE3) (p = .019) values were found in Group 1. In patients having fetuses with polymorphic variants on chromosome 9, a significantly lower PAPP-A values were observed compared to women with other fetal polymorphic variants (p = .048) or women having fetuses with normal karyotype (p = .007). Conclusions: Lower PAPP-A and higher uE3 levels were observed in women having fetuses with chromosomal polymorphisms, which might affect screening test results. Lower PAPP-A levels were apparent in women having fetuses with polymorphism on chromosome 9.