In a subgroup analysis, we excluded confirmed phenocopies of HCM, including lysosomal storage disorders (n = 1), glycogen storage disorders (n = 1), PRKAG2 cardiomyopathy (n = 3), RASopathies (mainly Noonan syndrome, n = 9; cardiofaciocutaneous syndrome, n = 1), mitochondrial diseases (n = 2), and other rare conditions (n = 4). Here, PRKAG2 is linked to Noonan syndrome.