NALCN and Global developmental delay: Biallelic NALCN variants have been described in individuals with infantile hypotonia, severe psychomotor retardation, characteristic facies 1 and disordered respiratory rhythm with central apnea (IHPRF1) [322,323], while heterozygous de novo NALCN missense variants in the S5/S6 pore-forming segments lead to congenital contractures of the limbs and face, hypotonia, and global developmental delay (CLIFAHDD) [324].