In a recent study performed by the Pediatric Cardiovascular Genomics Consortium (PCGC) of 362 cases of critical congenital cardiac defects including 60 patients with HLHS, de novo mutations were noted in 8 genes involved in the regulation of methylation of histone H3, lysine 4 (H3K4),98 including KMT2D (associated with Kabuki syndrome); CHD7 (associated with CHARGE syndrome); KDM5A and KDM5B (H3K4 demethylases); WDR5, and RNF20, UBE2B, and USP44, which are involved in histone ubiquitination. The gene discussed is KMT2D; the disease is Kabuki syndrome.