A novel DLG4 variant causes DLG4 -related synaptopathy with intellectual regression

DLG4 -related synaptopathy is a neurodevelopmental disorder caused by a DLG4 variant. We identified a novel de novo heterozygous frameshift variant, NM_001321075.3( DLG4 ):c.554_563del, in a Japanese girl. Intellectual regression without motor delay was observed at 2 years of age, and she was diagnosed with autism spectrum disorder and attention-deficit/hyperactivity disorder. Recognizing the possibility of DLG4 -related synaptopathy in patients with intellectual regression is important for ensuring an accurate diagnosis.