C9orf72 and amyotrophic lateral sclerosis: Gene-specific sex ratios and familial history for C9ORF72, SOD1, and TARDBP were examined in an expanded dataset of 2,301 Italian ALS patients.<h4>Results</h4>Sex-stratified burden testing revealed that rare variants in ALS genes were enriched in female cases versus controls (odds ratio [OR] 5.47, 95% confidence interval [CI] 1.60-34.29) but not in male cases.