The CLCN3 gene (located on chromosome 4q33) encodes the ClC-3 protein, a member of the CLC family of chloride channels and transporters. ClC-3 primarily functions as a chloride/proton exchanger in endosomal and lysosomal membranes. It is widely expressed in the brain and is important for regulating vesicular acidification and neuronal excitability.
Pathogenic variants include homozygous loss-of-function alleles (frameshift variants leading to absence of protein) and heterozygous de novo missense variants. Functional studies show that some missense alleles alter channel gating and ion transport properties, while others leave biophysical properties intact but are still associated with disease, suggesting multiple pathogenic mechanisms.
Animal studies support the role of CLCN3 in brain development and maintenance. Clcn3 knockout mice display mice display severe neurodegeneration, thin corpus callosum, and white matter loss, closely mirroring the severe neurodevelopmental disorder in individuals with recessive genotype.
CLCN3