TMEM63C and Intellectual disability: Here, we identified biallelic variantsin the transmembrane protein 63C (TMEM63C) gene, encoding a predictedosmosensitive calcium-permeable cation channel, in individuals with hereditary spasticparaplegias associated with mild intellectual disability in some, but not all cases.Biochemical and microscopy analyses revealed that TMEM63C is an endoplasmicreticulum-localized protein, which is particularly enriched at mitochondria–endoplasmicreticulum contact sites.