ALPK3 and cardiomyopathy: One recently described cardiomyopathy arises from variants in ALPK3, which encodes the muscle-specific protein α-kinase 3.3 Recessive ALPK3 variants (loss-of-function or deleterious missense) cause cardiomyopathy late in gestation or infancy with biventricular dilatation and depressed contractile function.3–8 Disease progression is often rapid with hemodynamic decompensation and death in childhood.