ALS2 and juvenile amyotrophic lateral sclerosis: JALS has a rare frequency with an estimated prevalence of 1 case per 1.000.000 and generally associated with autosomal recessive or autosomal dominant inheritance with highly penetrant genetic variants in causative genes as ALS2, SPG11, SIGMAR1, SETX, SOD1, UBQLN2 and FUS [23–25].