C9orf72 and amyotrophic lateral sclerosis: The cumulative analyses suggested that C9orf72 repeat expansions were significantly correlated with the risk of ALS (OR = 71.38, 95% CI = 41.83–121.82, and p < 0.00001). C9orf72 repeat expansions were related to the risk of both familial and sporadic ALS (OR = 293.25, 95% CI = 148.17–580.38, and p < 0.00001; OR = 35.57, 95% CI = 19.61–64.51, and p < 0.00001).