West Syndrome Caused By a Chloride/Proton Exchange-Uncoupling CLCN6 Mutation Related to Autophagic-Lysosomal Dysfunction

Mol Neurobiol. 2021 Jun;58(6):2990-2999. doi: 10.1007/s12035-021-02291-3. Epub 2021 Feb 16.


Vesicular chloride/proton exchangers of the CLC family are critically involved in the function of the endosomal-lysosomal pathway. Their dysfunction leads to severe disorders including intellectual disability and epilepsy for ClC-4, Dent's disease for ClC-5, and lysosomal storage disease and osteopetrosis for ClC-7. Here, we report a de novo variant p.Glu200Ala (p.E200A; c.599A>C) of the late endosomal ClC-6, encoded by CLCN6, in a patient with West syndrome (WS), severe developmental delay, autism, movement disorder, microcephaly, facial dysmorphism, and visual impairment. Mutation of this conserved glutamate uncouples chloride transport from proton antiport by ClC-6. This affects organellar ion homeostasis and was shown to be deleterious for other CLCs. In this study, we found that upon heterologous expression, the ClC-6 E200A variant caused autophagosome accumulation and impaired the clearance of autophagosomes by blocking autophagosome-lysosome fusion. Our study provides clinical and functional support for an association between CLCN6 variants and WS. Our findings also provide novel insights into the molecular mechanisms underlying the pathogenesis of WS, suggesting an involvement of autophagic-lysosomal dysfunction.

Keywords: Autophagy; CLCN6; Chloride/proton exchanger; Lysosome; West syndrome.

Publication types

  • Case Reports

MeSH terms

  • Amino Acid Sequence
  • Autophagy / genetics*
  • Base Sequence
  • Child
  • Child, Preschool
  • Chloride Channels / chemistry
  • Chloride Channels / genetics*
  • Chlorides / metabolism*
  • Computer Simulation
  • HEK293 Cells
  • HeLa Cells
  • Humans
  • Infant
  • Infant, Newborn
  • Lysosomes / metabolism*
  • Male
  • Mutation / genetics*
  • Protons*
  • Spasms, Infantile / genetics*
  • Subcellular Fractions / metabolism


  • CLCN6 protein, human
  • Chloride Channels
  • Chlorides
  • Protons