High frequency of the TARDBP p.M337 V mutation among south-eastern Chinese patients with familial amyotrophic lateral sclerosis

Background Amyotrophic lateral sclerosis (ALS) is a devastating motor neuron disease characterized by substantial clinical and genetic heterogeneity. Thus far, only a few TARDBP -ALS families have been reported in China, and no mutation analysis has been reported in south-eastern China. Methods Seven index cases from ALS families negative for SOD1 and FUS mutations were screened by Sanger sequencing for TARDBP gene exons 2-6. TARDBP exon 6 was analysed in 215 sporadic ALS patients. Results Two TARDBP mutations in exon 6 (p.M337 V and p.G348C) were identified in 5 unrelated families. Four of these 5 families carried the same p.M337 V mutation (family 1II3, family 2II6, family 3II4, and family 4II4), and the p.G348C mutation was identified in family 5 (II5). Among the 215 sporadic patients, only a single nucleotide polymorphism (p.A366A) was detected in 5 patients, and no responsible mutation was identified. Among the TARDBP- linked familial ALS patients, the average age of onset was 57.0 ± 4.7 years, and a trend towards higher rates of bulbar (50.0%, 6/12) onset and upper limb (41.7%, 5/12) onset than lower rates of limb onset (8.3%, 1/12) was observed. Furthermore, ALS patients with TARDBP mutations showed a benign disease course, and the average survival was 106.5 ± 41.8 months ( n = 8). Conclusions We found a high frequency of the TARDBP p.M337 V mutation in familial ALS in south-eastern China. The TARDBP- linked ALS patients showed a benign disease course and prolonged survival.