A Natural History Comparison of SOD1-Mutant Patients with Amyotrophic Lateral Sclerosis between Chinese and German Populations

Abstract

Background: The gene coding the Cu/Zn superoxide dismutase ( SOD1 ) was the first-identified causative gene of amyotrophic lateral sclerosis (ALS), and the second most common genetic cause for ALS worldwide. The promising therapeutic approaches targeting SOD1 mutations are on the road. The purpose of the present study was to compare the mutational and clinical features of Chinese and German patients with ALS carrying mutations in SOD1 gene, which will facilitate the strategy and design of SOD1 -targeted trials.Methods: Demographic and clinical characteristics were collected from two longitudinal cohorts in China and Germany. Chinese and German patients carrying SOD1 mutations were compared with regard to mutational distribution, age of onset, site of onset, body mass index (BMI) at diagnosis, diagnostic delay, progression rate, and survival.Results: A total of 66 Chinese and 84 German patients with 69 distinct SOD1 mutations were identified. The most common mutation in both populations was p.His47Arg. It was found in 8 Chinese and 2 German patients and consistently showed a slow progression of disease in both countries. Across all mutations, Chinese patients showed a younger age of onset (43.9 vs 49.9 years, p=0.002), a higher proportion of young-onset cases (62.5% vs 30.7%, p<0.001) and a lower BMI at diagnosis (22.8 vs 26.0, p<0.001) compared to German patients. Although riluzole intake was less frequent in Chinese patients (28.3% vs 81.3%, p<0.001), no difference in survival between populations was observed (p=0.90). Across both cohorts, female patients had a longer diagnostic delay (15.0 vs 11.0 months, p=0.01) and a prolonged survival (248.0 vs 60.0 months, p=0.005) compared to male patients.Conclusions: Our data demonstrate the distinct mutational and clinical spectrums of SOD1 -mutant patients in Asian and European populations. Clinical phenotypes seem to be primarily influenced by mutation-specific, albeit not excluding ethnicity-specific factors. Further large-scale transethnical studies are needed to clarify determinants and modifiers of SOD1 phenotypes.