Amyotrophic lateral sclerosis 1
Is there a gene mutation that is more common than others for Amyotrophic Lateral Sclerosis?
There is not a specific genetic variant, or mutation, that causes the majority of amyotrophic lateral sclerosis (ALS). However, about 25-30% of familial ALS cases and a small percent of sporadic cases are caused by a specific type of genetic variation in the C9orf72 gene called a hexanucleotide repeat. The hexanucleotide repeat is a region which affected individuals have more repeated copies of the DNA sequence GGGGCC. More than 60 repeats of the GGGGCC sequence are generally considered to be disease-causing. The function of this gene is unknown. An additional 20% of familial ALS cases are caused by genetic variants in the SOD1 gene.