Genetic epidemiology of amyotrophic lateral sclerosis in Cyprus: a population-based study

Amyotrophic lateral sclerosis (ALS) is a devastating, uniformly lethal degenerative disease of motor neurons, presenting with relentlessly progressive muscle atrophy and weakness. More than fifty genes carrying causative or disease-modifying variants have been identified since the 1990s, when the first ALS-associated variant in the gene SOD1 was discovered. The most commonly mutated ALS genes in the European populations include the C9orf72, SOD1, TARDBP and FUS. Understanding the genetic causes of ALS within a population is becoming more significant, especially in light of the possible development of personalized medicine. Here, we provide clinical and genetic data on familial and sporadic ALS patients in a Greek-Cypriot population-based cohort. Eighty-nine ALS patients, including 21 familial ALS (fALS) (23.6%) and 68 sporadic ALS (sALS) (76.4%), provided the cohort for variant screening of the most common ALS-associated genes. Moreover, next-generation sequencing (NGS) was also performed to identify rare ALS variants, and in silico prediction tools were applied to predict the downstream effect of the variants detected in our study. The pathogenic hexanucleotide G₄C₂ repeat expansion in C9orf72 was the predominant genetic cause (22.47%) of ALS in our population, while variants in six additional ALS-associated genes were identified, including ALS2, TARDBP, FIG4, TBK1, GLT8D1, and BICD2.