The HCRTR1 and HCRTR2 genes have been investigated for association with disorders like narcolepsy, Alzheimer’s disease, and headache [23]; in particular, a 408 isoleucine to valine mutation in the HCRTR1 gene (rs2271933) is the most studied SNP [24]. Here, HCRTR1 is linked to early-onset autosomal dominant Alzheimer disease.