KMT2D and hypoplastic left heart syndrome: We considered whether these splice-altering variants altered 1 of 253 genes that have established or plausible roles in CHD based on analyses of patients and model organisms (Table S3).6,7 Two of 4 splice-altering variants identified in the CHD cohort altered KMT2D, causing Kabuki syndrome and 1 each in RSP24, causing Diamond-Blackfan anemia and in RBFOX2, a gene recurrently mutated in children with hypoplastic left heart syndrome (Table 1).