Atrial fibrillation (AF) is the most common sustained cardiac rhythm disturbance, affecting more than 2 million Americans, with an overall prevalence of 0.89%. The prevalence increases rapidly with age, to 2.3% between the ages of 40 and 60 years, and to 5.9% over the age of 65. The most dreaded complication is thromboembolic stroke (Brugada et al., 1997). For a discussion of genetic heterogeneity of atrial fibrillation, see 608583.

Renal hypomagnesemia-7 with or without dilated cardiomyopathy (HOMG7) is characterized primarily by renal salt wasting resulting in hypomagnesemia with secondary effects such as hypokalemia or hypocalcemia. Many patients develop nephrocalcinosis, although renal function is generally well-preserved. The age at onset is highly variable, ranging from infancy to young adulthood. A subset of patients develop severe dilated cardiomyopathy as early as in infancy, which may require heart transplant (Schlingmann et al., 2021). For a discussion of genetic heterogeneity of hypomagnesemia, see 602014.