Mutations in CNNM2 have been implicated in familial hypomagnesemia with symptoms including cardiac arrhythmias [28], while common variants of uncertain functions in GUCY1A3 have been implicated in hypertension by GWAS, and rare non-synonymous variants in disorders of vascular tone and myocardial infarction [29–34]. The gene discussed is CNNM2; the disease is cardiac arrhythmia.