EHMT1 and Kleefstra syndrome: Kleefstra Syndrome (KLEFS, OMIM #610253) is a rare genetic neurodevelopmental disorder caused by point mutations in EHMT1 (euchromatic histone-lysine N-methyltransferase 1) or, more frequently, by microdeletions of chromosomal region 9q34.3 (> 85% of cases), with loss of the entire gene [98].