C9orf72 Repeat Expansion
Autosomal dominant hexanucleotide repeat expansions in the C9orf72 gene have been associated frontotemporal dementia and/or amyotrophic lateral sclerosis (FTD; ALS; FTDALS1). The penetrance of FTD/ALS is associated with the length of hexanucleotide repeats. The contribution of missense variants in the C9orf72 gene is unclear. The scope of this assay is limited to repeat expansion analysis of this gene and may not reveal the exact number of repeats present in large expansions.