C9ORF72 repeat expansion: a genetic mutation associated with Amyotrophic Lateral Sclerosis

The advent of genome-wide sequencing and genotyping technologies has made significant contribution towards the understanding of Amyotrophic Lateral Sclerosis (ALS) genetics. The etiology of about 70% of the familial cases and 11% of the sporadic ALS cases can now be attributed to various genes. Since the identification of an expanded hexanucleotide repeat in the intronic region of C9ORF72 as the most common mutation associated with fALS, sALS and FTD, researchers have focused to understand the function and toxicity of this gene. In this review, we discuss the biology of C9ORF72 and describe its genetic and functional association with ALS.