Evaluation of demographic, clinical characteristics, and genetic polymorphism as risk factors for pelvic organ prolapse in Brazilian women

Abstract

Objective: Verify the association between genital prolapse, other risk factors and a polymorphism in exon 31 of the collagen III-a1 gene (COL3A1).

Setting: The etiology of genital prolapse is multifactorial, and genetic defects have been proposed. Also, there is evidence that changes in collagen may be responsible for defects in pelvic floor support. The exon 31 polymorphism results in structural changes in the triple helical of the collagen and appears to lead to abnormal synthesis of type III collagen.

Design: Basic science study.

Population: The studied group consisted of 107 patients with stage III and IV genital prolapse (POP-Q). The control group included 209 women with stage 0 and I prolapse.

Methods: After extracting genomic DNA from the peripheral blood, the exon 31 COL3A1 polymorphism was typed by restriction fragment length polymorphism analysis.

Main outcome measures: Association between genital prolapse and exon 31 COL3A1 polymorphism.

Results: No statistically significant differences in genotype and allele frequencies were found between cases and controls (P = 0.75 and 0.66, respectively). Multiple logistic regression analyses identified age (OR = 1.05; 95%CI = 1.01-1.10), BMI (OR = 1.09; 95%CI = 1.01-1.17), presence of at least one vaginal delivery (OR = 7.22; 95%CI = 1.84-28.27), positive family history of POP (OR = 2.27; 95%CI = 1.05-4.93) and a macrosomic foetus (OR = 2.91; 95%CI = 1.24-6.79) as independent risk factors for genital prolapse. In contrast, the number of caesarean deliveries was found to be an independent protective factor (OR = 0.43; 95%CI = 0.24-0.78).

Conclusions: The type III collagen exon 31 polymorphism is not a risk factor for pelvic genital prolapse in this sample.