To understand if Mexiletine will restore normal colonic motility in a patient with a missense mutation in SCN5A, which encodes a voltage-sensitive sodium channel NaV1.5 as it is known to rescue certain expression defects of NaV1.5 in vitro.
To understand if Mexiletine will restores normal colonic motility in a patient with irritable bowel syndrome - constipation (IBS-C) and a genetic mutation in SCN5A.