Mutations in UBQLN2 and SIGMAR1 genes are rare in Korean patients with amyotrophic lateral sclerosis

Mutations in the UBQLN2 and SIGMAR1 genes were recently identified in X-linked dominant amyotrophic lateral sclerosis and/or frontotemporal dementia (ALS and/or FTD) and FTD and/or motor neuron disease, respectively. Subsequent studies, however, found that UBQLN2 mutations were rare, and the pathogenicity of SIGMAR1 mutation in FTD and/or motor neuron disease was controversial. In the present study, we analyzed mutations in the UBQLN2 and SIGMAR1 genes in a Korean cohort of 258 patients with familial ALS (n= 9) or sporadic (sALS; n= 258) ALS. One novel UBQLN2 variant (p.D314E) was observed in 2 patients with sALS and 5 of 727 controls indicating that this variant might be a rare polymorphism rather than a disease-causing mutation. A novel SIGMAR1 gene variant in the 3'-untranslated region (c.*58T>C) was found in 1 sALS and was absent in 727 control samples. Taken together, our data suggest that causative mutations in the UBQLN2 and SIGMAR1 genes are rare in Korean patients with either familial or sporadic ALS.