Variants in the zinc transporter TMEM163 cause a hypomyelinating leukodystrophy.

Document Type

Article

Publication Date

12-19-2022

Identifier

DOI: 10.1093/brain/awac295

Abstract

Hypomyelinating leukodystrophies comprise a subclass of genetic disorders with deficient myelination of the CNS white matter. Here we report four unrelated families with a hypomyelinating leukodystrophy phenotype harbouring variants in TMEM163 (NM_030923.5). The initial clinical presentation resembled Pelizaeus-Merzbacher disease with congenital nystagmus, hypotonia, delayed global development and neuroimaging findings suggestive of significant and diffuse hypomyelination. Genomic testing identified three distinct heterozygous missense variants in TMEM163 with two unrelated individuals sharing the same de novo variant. TMEM163 is highly expressed in the CNS particularly in newly myelinating oligodendrocytes and was recently revealed to function as a zinc efflux transporter. All the variants identified lie in highly conserved residues in the cytoplasmic domain of the protein, and functional in vitro analysis of the mutant protein demonstrated significant impairment in the ability to efflux zinc out of the cell. Expression of the mutant proteins in an oligodendroglial cell line resulted in substantially reduced mRNA expression of key myelin genes, reduced branching and increased cell death. Our findings indicate that variants in TMEM163 cause a hypomyelinating leukodystrophy and uncover a novel role for zinc homeostasis in oligodendrocyte development and myelin formation.

Journal Title

Brain : a journal of neurology

Volume

145

Issue

12

First Page

4202

Last Page

4209

MeSH Keywords

Humans; Pelizaeus-Merzbacher Disease; Mutation, Missense; Myelin Sheath; Zinc; Membrane Proteins

Keywords

Humans; Pelizaeus-Merzbacher Disease; Mutation, Missense; Myelin Sheath; Zinc; Membrane Proteins

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