Polymorphism in the SCN9A Voltage-Gated Sodium Channel Gene Associated With Interstitial Cystitis/Bladder Pain Syndrome

Abstract

To determine whether an association exists between interstitial cystitis/bladder pain syndrome (IC/BPS) and a nonsynonymous single nucleotide polymorphism in the SCN9A voltage-gated sodium channel gene previously associated with other chronic pain syndromes. Germline deoxyribonucleic acid was sampled from archived bladder biopsy specimens from patients with a documented diagnosis of IC/BPS. Deoxyribonucleic acid from hysterectomy specimens was obtained as a control population. The genotype of single nucleotide polymorphism rs6746030 was determined by deoxyribonucleic acid sequencing after polymerase chain reaction amplification. Contingency analysis of genotypes was performed using Pearson's chi-square test and Fisher's exact test. Polymerase chain reaction product was obtained from 26 of 31 control specimens and from 53 of 57 IC/BPS biopsy specimens. Of the 26 control subjects, 3 (11.5%) were genotype AG and 23 were GG. In contrast, AA or AG genotypes were present in 21 of 53 (39.6%) patients with IC/BPS, a statistically significant difference compared with the controls (Pearson's chi-square, P=.036). Similarly, the A allele was at a greater frequency in the IC/BPS group using Fisher's exact test (P=.009). These data strongly suggest that pain perception in at least a subset of patients with IC/BPS is influenced by this polymorphism in the SCN9A voltage-gated sodium channel.