unassigned: To investigate the pathogenicity of 2 novel variations, report the clinical and neuroimaging findings, and review the available literature. unassigned: Physical examinations, structural neuroimaging studies, and exome sequence analysis were performed. KDM5C constructs were used to study the effect of the variations in transfected cells. unassigned: We identified 2 novel variations c.2233C>G and c.3392_3393delAG in the gene harboring from 2 Chinese families with X-linked intellectual disability (ID). The affected male patients exhibited severe ID, short stature, and facial dysmorphism. The 1 with c.3392_3393delAG additionally had epilepsy and autistic spectrum disorder (ASD). Transiently transfected mutant KDM5C constructs both reduced protein expression and stability and decreased histone demethylase activities in cells. Reviewing the available literature, we found that the associated ASD tended to occur in patients with variations near the C-terminus of KDM5C. unassigned: We report the clinical, molecular genetic, and pathologic features in patients with novel variations of . The variability of the clinical phenotype in addition to an ID may associate with altered particular parts of KDM5C.