ATXN1 and amyotrophic lateral sclerosis: Independent of biallelic ‘AAGGG’ repeat expansions that cause a neurodegenerative phenotype such as CANVAS with high penetrance, other RFC1 repeat configurations could be potential genetic risk factors for a neurodegeneration such as ALS as it is known for certain intermediate and pathogenic repeat expansions such as in ATXN1, ATXN2 and HTT [37–39].