Fibrosis as a common trait in amyotrophic lateral sclerosis tissues

Amyotrophic lateral sclerosis(ALS)is a highly aggressive adult-onset neurodegenerative disease caused by the progressive loss of upper and lower motor neurons.Clinically,it causes irreversible muscle atrophy and spasticity,leading to death due to respiratory failure,usually within 2–5 years after the first symptom onset.Approximately 85%of ALS cases are classified as sporadic,while the remaining 15%are of familial origin,but the overall clinical and molecular features of the disease are almost undistinguishable in the two forms.The majority of familial ALS cases are caused by pathogenic variants of C9orf72,SOD1,TARDBP,FUS,ANG and OPTN genes that are inherited by a Mendelian pattern and display high penetrance(Kiernan et al.,2020).