Mutations in UNC80, Encoding Part of the UNC79-UNC80-NALCN Channel Complex,Cause Autosomal-Recessive Severe Infantile Encephalopathy

Brain channelopathies represent a growing class of brain disorders that usually result in paroxysmal disorders, although their role in other neurological phenotypes, including the recently described NALCN-related infantile encephalopathy, is increasingly recognized. In three Saudi Arabian families and one Egyptian family all affected by a remarkably similar phenotype (infantile encephalopathy and largely normal brain MRI) to that of NALCN-related infantile encephalopathy, we identified a locus on 2q34 in which whole-exome sequencing revealed three, including two apparently loss-of-function, recessive mutations in UNC80. UNC80 encodes a large protein that is necessary for the stability and function of NALCN and for bridging NALCN to UNC79 to form a functional complex. Our results expand the clinical relevance of the UNC79-UNC80-NALCN channel complex.