Association between superoxide dismutase 1 mutations and clinical phenotypes in Chinese patients with familial amyotrophic lateral sclerosis

Objective To identify the patterns of population distribution and the relationship of copper-zinc superoxide dismutase 1 (SOD1) mutations and clinical phenotypes in Chinese patients with familial amyotrophic lateral sclerosis (FALS). Methods The clinical data of 43 FALS families from 2008 to 2011 were collected, SOD1 gene mutations in the probands were screened with PCR and direct sequencing, and the correlations of genotype-phenotype were analyzed. Results All 43 FALS families were autosomal dominant inheritance. The male to female ratio for probands was 1∶0.6, and the average onset age was (48.1±11.8) years. Upper limb onset accounted for 53.5%, lower limb onset 41.9%, and bulbar onset 4.6%. Nine mutation types including 8 missense mutations and 1 deletion mutation were detected in 10 probands. The detection rate of SOD1 mutations in this cohort was 23.3%. Conclusions The study reported the correlations of genotype-phenotype of SOD1 in a larger group of Chinese FALS patients. Two novel mutations were found including one deletion mutation. SOD1 mutations increased from 11 to 19 in Chinese FALS. For SOD1 patients, lower motor neuron signs usually predominated. Most clinical phenotypes of one mutation varied greatly in different families even in the same family. Key words: Amyotrophic lateral sclerosis; Superoxide dismutase; Mutation; Copper; Zinc;  Phenotype