NOTCH2NLC is one of the three human-specific NOTCH2-related genes (NOTCH2NLA, NOTCH2NLB, and NOTCH2NLC) in 1q21.1, highly expressed in the brain and thought to be involved in the evolutionary expansion of the human brain.30, 32 Thus, NIID represents a genetic disorder caused by an expanded repeat in a human-specific gene. This evidence concerns the gene NOTCH2NLA and neuronal intranuclear inclusion disease.