Whole-genome analysis of monozygotic twins discordant for type 1 narcolepsy

Narcolepsy type 1 (NT1) is a rare and chronic neurological disease characterized by sudden sleep attacks, overwhelming daytime drowsiness, and cataplexy. To contribute to the understanding of NT1 genetic causes, here we describe a whole-genome analysis of a monozygotic twin pair discordant for NT1. Our study revealed that although both twins have the same pathogenic mutations in NT1 associated genes (such as HLA-DQB1*06:02:01, HLA-DRB1*11:01:02/*15:03:01) the unaffected twin has mutations in genes outside the HLA loci that could be suppressing the NT1 phenotype. These results support the notion that NT1 has an immunological basis but that protective mutations in non-HLA might interfere with the clinical manifestation of the disease.