Phenotypic and genotypic features of patients diagnosed with ALS in the city of Sakarya, Turkey

Abstract

Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disease leading to motor neuron damage. In this study, the clinical, demographic, and genetic features of ALS patients in the city of Sakarya, Turkey, were investigated. Patients with an established diagnosis of ALS according to the Awaji criteria were included. Age, sex, age at onset of ALS, initial complaints, consanguineous marriage, and genetic features were retrospectively investigated. Conventional genetic analysis and NGS were used for molecular evaluation of patients. A total of 55 probands (10 familial, 45 sporadic) in whom ALS was suspected due to their phenotypic features were included. Thirty-two patients were male (58.2%), and 23 were female (41.8%); their mean ages were 62.65 ± 13years. The mean age of onset for 37 familial patients from 10 families was 49.9years. Two cases had juvenile-onset. Fourteen (25.5%) bulbar-onset versus 40 (72.7%) limb-onset patients were detected; one patient had both. Six (10.9%) patients showed marked frontotemporal dementia. Twenty-nine (52.7%) patients died during the follow-up period. Genetic analysis identified causative variants in eleven cases, carrying variants in six different ALS genes (C9orf72, SOD1, VCP, SPG11, TBK1, and SH3TC2). Genetic investigations have revealed more than 40 genes to be involved in the pathogenesis of ALS. Our relatively small study cohort restricted to one province of Turkey, however, prone to migration, consists of 10/55 familial ALS cases, which harbor two rare (SH3TC2-p.Met523Thr and TBK1-p.Glu643del) and two novel (SPG11-p.Lys656Valfs*11 and VCP-p.Arg191Pro) mutations contributing to the literature.