Congenital Heart Defect
Gene: EHMT2
EHMT1 and EHMT2 encode histone lysine methyltransferase 1 (GLP) and 2 (G9a) respectively. Together, they form heteromeric GLP/G9a complexes which catalyse H3K9 mono‑ and di‑methylation. EHMT1 is associated with Kleefstra syndrome 1.
PMID 42386776 report 7 unrelated individuals with de novo heterozygous EHMT2 missense and inframe deletion variants causing a Kleefstra‑like neurodevelopmental syndrome, with psychomotor developmental delay, intellectual disability, absent speech, structural brain anomalies, hypotonia, dental anomalies and behavioural and sleep difficulties. Additional features also included recognisable facial dysmorphism (hypertelorism, synophrys, flat face, everted lips and protruding jaw) and cardiac anomalies (septal defects, pulmonic valve stenosis, aortic coarctation). All variants are absent from gnomAD. Episignature partially overlaps with Kleefstra syndrome 1 but was reported to form its own distinct profile. Biochemical assays show severe loss of G9a activity in fibroblast cell culture collected from patient 2 (EHMT2 c.3229G>T). A heterozygous knock‑in mouse model with a patient derived variant (Ehmt2 +/del_1076-1079) recapitulated the neurobehavioural and craniofacial phenotype. In vitro studies show that patient variants encode for structurally stable G9a proteins which are catalytically incompetent due to aberrant interactions either with histone H3 tail or with S-adenosylmethionine. The proposed mechanism is dominant negative effect on the GLP/G9a complexes.
PMID 3967492 and 42434347 describe two unrelated probands with biallelic loss‑of‑function EHMT2 variants presenting with a Kleefstra‑like neurodevelopmental disorder that includes developmental delay, facial dysmorphism, vertebral anomalies and congenital heart disease. A DNA‑methylation episignature matching Kleefstra syndrome 1 was reported for both patients.
Sources: LiteratureCreated: 17 Aug 2026, 1:12 p.m. | Last Modified: 17 Aug 2026, 1:21 p.m.
Panel Version: 2.448
Mode of inheritance
BOTH monoallelic and biallelic, autosomal or pseudoautosomal
Phenotypes
Kleefstra syndrome, MONDO:0012455, EHMT2-related
Publications
Gene: ehmt2 has been classified as Green List (High Evidence).
Gene: ehmt2 has been classified as Green List (High Evidence).
gene: EHMT2 was added gene: EHMT2 was added to Congenital Heart Defect. Sources: Literature Mode of inheritance for gene: EHMT2 was set to BOTH monoallelic and biallelic, autosomal or pseudoautosomal Publications for gene: EHMT2 were set to 42434347; 42386776; 39674972 Phenotypes for gene: EHMT2 were set to Kleefstra syndrome, MONDO:0012455, EHMT2-related