Short tandem repeat expansions in are absent in cohorts of familial and sporadic amyotrophic lateral sclerosis patients of European ancestry.

In patients of Asian ancestry, a heterozygous CGG repeat expansion of >100 units in is the cause of oculopharyngodistal myopathy type 1 (OPDM1). Repeat lengths of between 61 and 100 units have been associated with rare amyotrophic lateral sclerosis (ALS) cases of Asian ancestry, although with unusually long disease duration and without significant upper motor neuron involvement. This study sought to determine whether CGG repeat expansions were also present in ALS patients of European ancestry. Whole-genome sequencing data from 608 sporadic ALS patients, 35 familial ALS probands, and 4703 neurologically normal controls were screened for CGG expansions using ExpansionHunter v4. All individuals had CGG repeat lengths within the normal range of 3-25 units. To date, CGG repeat expansions have not been reported in ALS patients of European ancestry and may be limited to rare ALS patients of Asian ancestry and atypical clinical presentations.