HTRA2 and amyotrophic lateral sclerosis: Unal Gulsuner et al. (2014) reported that High Temperature Requirement Protein A2 (HTRA2) is responsible for hereditary essential tremor and that homozygotes for this allele develop Parkinson disease. And Fused in sarcoma (FUS) mutations have been found in individuals with ALS/PD (Yan et al., 2010).