TRPM8 polymorphisms associated with increased risk of IBS-C and IBS-M

Maria Henström, Fatemeh Hadizadeh, Arthur Beyder, Ferdinando Bonfiglio, Tenghao Zheng, Ghazaleh Assadi, Joseph Rafter, Luis Bujanda, Lars Agreus, Anna Andreasson, Aldona Dlugosz, Greger Lindberg, Peter T. Schmidt, Pontus Karling, Bodil Ohlsson, Nicholas J. Talley, Magnus Simren, Susanna Walter, Mira Wouters, Gianrico FarrugiaMauro D'Amato

Research output: Contribution to journalLetterOtherpeer-review

35 Citations (Scopus)

Abstract

Recently in Gut, genetic variation affecting ion channels activity has been highlighted in relation to bowel function and the biology of stool frequency.1 It is also known that 2% of patients with IBS carry functional missense mutations in the voltage-gated channel NaV1.5 (SCN5A gene).2 Hence, channelopathies represent potential abnormalities underlying GI dysfunction and IBS. We inspected data from our previous genome-wide association study (GWAS) of IBS,3 in relation to 27 genes whose ion channel products contribute to GI sensorimotor development and function, visceral sensation and GI motility (see online supplementary table S1). Significant (uncorrected) results were detected for four genes (calcium voltage-gated channels CACNA1A and CACNA1E, and transient receptor potential channels TRPV3 and TRPM8; see online supplementary figure S1), which were selected for replication analyses in an independent set of IBS cases (N=386) and controls (N=357) (see online supplementary material methods). A sex-adjusted logistic regression analysis of genotype data from this cohort (see online supplementary material methods) detected significant associations for TRPM8, and a meta-analysis of GWAS and replication yielded (i) strongest evidence of association at this locus, (ii) no statistical heterogeneity (Cochran's Q test p>0.05) and (iii) same direction of genetic risk effects in the two studies (table 1). Rome III IBS-subtype information available for the replication cohort revealed TRPM8 single nucleotide polymorphisms (SNP) to impact IBS risk exclusively in the IBS-C and IBS-M types, with strongest evidence obtained from their combined analysis (table 1). This prompted us to investigate the relationship between TRPM8 and GI motility in the Population-based Colonoscopy study (PopCol),4 focusing on IBS-free individuals (N=120) who kept weekly records of their defaecation episodes based on the Bristol Stool Form Scale (BSFS; see online supplementary material methods). A Spearman correlation analysis revealed all IBS-C/M risk alleles to be consistently associated with harder stools, showing progressively decreasing frequencies from lower to upper average BSFS quartile groups, while opposite results were obtained for protective alleles (figure 1).
Original languageEnglish
Pages (from-to)1725-1727
Number of pages3
JournalGut
Volume66
Issue number9
DOIs
Publication statusPublished - 1 Sept 2017
Externally publishedYes

Keywords

  • CONSTIPATION
  • GENETICS
  • ION CHANNELS
  • IRRITABLE BOWEL SYNDROME
  • POLYMORPHIC VARIATION

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