De novo loss-of-function variants of ASH1L are associated with an emergent neurodevelopmental disorder.

De novo variants of ASH1L, which encodes a histone methyltransferase, have been reported in a few patients with intellectual disability and autistic features. Here, we identified a novel de novo frame-shift variant, c.2422_2423delAAinsT which predicts p.(Lys808TyrfsTer40), in ASH1L in a patient with multiple congenital anomalies (MCA), fine motor developmental delay, learning difficulties, attention deficit hyperactivity disorder, sleep apnea, and scoliosis. This frame-shift variant is expected to result in loss-of-function. Our report provides further evidence to support loss-of-function alterations of ASH1L as causative for an emergent neurodevelopmental syndrome characterized by MCA, intellectual disability, and behavioral problems, and further delineates this genetic disorder.