A repeat expansion in the gene encoding junctophilin-3 is associated with Huntington disease-like 2

We recently described a disorder termed Huntington disease-like 2 (HDL2) that completely segregates with an unidentified CAG/CTG expansion in a large pedigree (W)(1). We now report the cloning of this expansion and its localization to a variably spliced exon of JPH3 (encoding junctophilin-3), a gene involved in the formation of junctional membrane structures.