Date Published: April 11, 2019
Publisher: Public Library of Science
Author(s): Valter D. Cassão, Sabrina T. Reis, Ruan Pimenta, Marcos Lucon, Katia R. M. Leite, Miguel Srougi, Homero Bruschini, Peter F.W.M. Rosier.
Interstitial Cystitis (IC) is a chronic condition diagnosed based on the presence of symptoms, such as suprapubic/ pelvic pain, pressure or discomfort in association with urgency and increased urinary frequency. Confusable diseases must be excluded. However, there is no objective test or marker to establish the presence of the disease. Diagnosis and patient management is often difficult, given the poor understanding of IC pathogenesis and its unknown etiology and genetics. As an attempt to find biomarkers related to IC, we assessed the association between 20 selected single nucleotide polymorphism (SNPs) with IC and pain severity.
To assess the presence of SNPs in IC patients’ blood samples and correlate them with the disease and chronic pain condition.
A case-control study was conducted. We selected 34 female patients with IC diagnosed according to NIDDK criteria and 23 patients in the control group (previously healthy women with only stress urinary incontinence). IC patients were allocated into two groups according to reported chronic pain severity. We selected the following SNPs for analysis: rs1800871, rs1800872, rs1800896, rs1800471, rs1800629, rs361525, rs1800497, rs6311, rs6277, rs6276, rs6313, rs2835859, rs11127292, rs2243248, rs6887695, rs3212227, rs1799971, rs12579350, rs3813034, and rs6746030. Genotyping was performed by real-time PCR (q-PCR).
The polymorphic allele of SNP rs11127292 exhibited a higher frequency in subjects with IC than in controls (p:0.01). The polymorphic allele of SNP rs6311 was more frequent in patients with severe pain (p:0.03). The frequency of the wild-type allele of SNP rs1799971 was higher in patients with mild to moderate pain (p:0.04).
The results indicated differences in SNP frequency among subjects, suggesting that SNPs could serve either as a marker of IC or as a marker of pain severity in IC patients. The study showed promising results regarding IC and polymorphism associations. These associations have not been previously reported.
Interstitial Cystitis (IC) or Painful Bladder Syndrome (PBS) is a debilitating chronic pelvic pain condition primarily based on symptoms of bladder-related pain, urgency, frequency and nocturia. The etiology is still unknown. Any other confounding urologic disease must be excluded [1,2]. Initially, considered a bladder-limited syndrome, focused on highly specific cystoscopic findings, this condition has recently been regarded as a systemic chronic pain syndrome with the main symptoms related to the bladder [1–6].
PCR products from the 20 selected SNPs were detected in all DNA specimens from 34 IC/PBS patients and 23 controls. Genotypes and allele distribution were compared.
This study attempted to correlate SNPs to IC/PBS and to pain severity in these patients. Associations were found in three of the 20 tested SNPs. One of them, rs11127292, was associated with the disease itself. Of the other two, rs6311 was associated with the cases with severe pain, and rs1799971 with mild to moderate pain patients.
SNP rs11127292 was more prevalent in the IC/PBS group than in the control group (p = 0.01).
Subjects in both groups provided written informed consent to participate the study and allowed their biological samples to be genetically analyzed. Approval for the study was given by the Institutional Board of Ethics (CAPPesq–Comissão de Ética para Análise de Projetos de Pesquisa) under the number 796/015.