ALS: amyotrophic lateral sclerosis; BVVL: Brown-Van Vialetto-Van Laere syndrome; CIDP: chronic inflammatory demyelinating polyradiculoneuritis; SBMA: Kennedy's disease (bulbospinal muscular atrophy); ASC3: Machado-Joseph's disease (spinocerebellar ataxia type 3); TTR-FAP: familial amyloid polyneuropathy; n, number of cases reported per article; Cp. This evidence concerns the gene TTR and bulbospinal muscular atrophy.