C9orf72 and amyotrophic lateral sclerosis: Interestingly enough, when these C9orf72 KO rats were treated with low doses of kainic acid for four weeks, they developed significant MN death that was accompanied by progressive motor deficits, suggesting that C9orf72 LoF could trigger sensitization of MN to other risk factors, such as excitotoxicity, to induce ALS.