Key result
Subjects with an SCN5A mutation had a significantly higher prevalence of GI symptom complexes compared to controls (65% vs 28%; OR 5.2; 95% CI 1.5-18.3).
Why the study?
Are cardiac channelopathy-associated mutations in SCN5A or KCNH2 associated with GI symptom complexes in families of patients with long QT syndrome?
Cross-Sectional (n=219)
Are cardiac channelopathy-associated mutations in SCN5A or KCNH2 associated with GI symptom complexes in families of patients with long QT syndrome?
Odds Ratio: 5.2 (95% CI 1.5–18.3)
Absolute Event Rate: 65% vs 28%
This study provides the first evidence suggesting an association between SCN5A-encoded cardiac channelopathies (long QT syndrome) and gastrointestinal symptoms.
SCN5A mutations may link to GI symptoms in LQTS families; hypothesis-generating and requires prospective confirmation before clinical consideration.
OBJECTIVES: Recently, two ion channels associated with congenital long QT syndrome, the SCN5A-encoded Nav1.5 sodium channel and the KCNH2-encoded HERG potassium channel (IKr), have been found on gastrointestinal smooth muscle and interstitial cells of Cajal. The aim of this study was to determine if the cardiac channelopathy-associated mutations in SCN5A or KCNH2 are associated with GI symptom complexes. METHODS: Mayo Clinic's Sudden Death Genomics Laboratory performed comprehensive mutational analysis on index patients referred for long QT syndrome genetic testing and their family members thus establishing a cohort of families for which the genotype status for SCN5A or KCNH2 is known. A valid GI symptom questionnaire was mailed to all family members (both genotype positive and genotype negative) in this cohort. The association between cardiac channel genotype and GI symptoms was assessed by logistic regression adjusted for age and sex. RESULTS: Two hundred and nineteen (43% of 529) subjects returned the questionnaire. Fifty percent of the subjects with an SCN5A mutation reported abdominal pain compared to only 13% of controls (OR 5.7; 95% CI 1.3-24.4). Over 65% of subjects with an SCN5A mutation reported a GI symptom complex compared to 28% of controls (OR 5.2; 95% CI 1.5-18.3). No associations with KCNH2 genotype status were detected. CONCLUSIONS: This study is the first to suggest an association between a well-defined cardiac channelopathy and GI symptoms. The role of sodium channelopathies in the pathogenesis of digestive diseases merits exploration.
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Locke et al. (2006) conducted a cross-sectional in SCN5A-Encoded Cardiac Channelopathy (n=219). SCN5A mutation vs. Controls was evaluated on GI symptom complex (OR 5.2, 95% CI 1.5-18.3). Subjects with an SCN5A mutation had a significantly higher prevalence of GI symptom complexes compared to controls (65% vs 28%; OR 5.2; 95% CI 1.5-18.3).
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