Slowly progressing Amyotrophic lateral sclerosis associated with the F21L variant in the SOD1 gene: Demographic and clinical characteristics.

Introduction/objective: Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease in which genetic variants can significantly influence clinical presentation and prognosis. This study aims to describe the demographic and clinical characteristics of ALS patients carrying the SOD1: c.63C > G (p.Phe21Leu) [NM_000454.4] variant, as treated at a national reference center in Colombia.

Methods: A descriptive study was conducted on patients identified with the SOD1: c.63C > G (p.Phe21Leu) [NM_000454.4] variant, selected from the database of a neuromuscular disease center in Colombia. Demographic and clinical data were collected through medical records and patient interviews. Molecular analysis was performed using PCR and automated sequencing to confirm the presence of the variant.

Results: Eleven patients with SOD1: c.63C > G (p.Phe21Leu) [NM_000454.4] variant were identified. The mean age at onset was 48.4 years, with a mean disease duration of 76.7 months. The majority (90.9%) exhibited a slowly progressive course, predominantly with spinal onset and no cognitive impairment. Bulbar symptoms developed in 72.2% of the patients, and 81.8% required noninvasive ventilation. A family history of ALS or other neurodegenerative disorders was present in 54.5% of the patients.

Conclusions: The SOD1: c.63C > G (p.Phe21Leu) [NM_000454.4] variant is associated with a slowly progressive ALS phenotype, characterized by predominant lower motor neuron involvement and delayed onset of bulbar and respiratory symptoms. This variant appears to be predominantly distributed in central Colombia. Early detection of this variant may enable timely interventions and personalized care plans. Further research is required to establish a definitive causal relationship between this variant and the observed clinical course.