Novel nonsense mutation in UNC80 in a Turkish patient further validates the sociable skill and severe gastrointestinal problems as part of disease spectrum

NALCN channelosome complex contributes to maintaining resting membrane potential. The complex has four domains including two intracellular domains (UNC79 and UNC80), one transmembrane domain (NALCN) and one extracellular domain (FAM155A). Mutations in UNC80 were previously linked to infantile hypotonia with psychomotor retardation and characteristics facies 2. A 6-year-old male with neurodevelopmental disorder was referred for clinical exome sequencing. Sanger sequencing was conducted for variant confirmation and segregation analysis. The index had severe to profound neurodevelopmental delay, progressive failure to thrive, severe constipation and reflux, and sociable skills. Trio exome sequencing identified a homozygous c.6495G > A change causing p.Trp2165Ter in UNC80 in the proband. The variant was novel and predicted to be deleterious. We reported a novel nonsense mutation in UNC80. Our case also established the association between, and sociable skills and severe gastrointestinal problems