A 4-year-old boy with severe intellectual disability (ID) and characteristics of autism was found to have a de novo 1.9-Mb microdeletion in 7q31.33q32.1, in which LRRC4, GRM8, and 11 other genes were included. GRM8 is associated with attention deficit hyperactivity disorder. LRRC4 is related to synaptic cell adhesion molecules, some of which are associated with autism. The deletion of LRRC4 may be responsible for the severe ID and characteristics of autism observed in the present patient.