Clinical and genetic determinants of survival in amyotrophic lateral sclerosis patients from North India.

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease characterized by progressive motor neuron degeneration, with significant clinical and genetic variability. While the role of genetic factors is well-established in ALS pathogenesis, their impact on survival outcomes remains poorly understood, particularly in the Indian population. We performed whole-exome sequencing in 159 ALS patients from North India (familial = 2, sporadic = 157). Clinical parameters, including age at onset, site of onset, sex, family history and survival, were recorded. Males exhibited shorter survival than females, but did not achieve statistical significance (median: 48 versus 60 years, P = 0.05). Bulbar-onset patients developed ALS at a significantly older age (mean: 59.7 versus 54 years, P = 0.007) and experienced poorer survival outcomes than spinal-onset patients (median: 48 versus 60 months, P = 0.03). A small subset of ALS patients (6.3%, n = 10) had very long survival duration of more than 10 years. We identified 102 genetic variants in 92 ALS patients, of which 45 variants were novel. According to American College of Medical Genetics and Genomics guidelines, 13.5% of total variants were pathogenic, 19.8% were likely pathogenic, and 66.7% were variants of uncertain significance. The presence of genetic variations was significantly associated with delayed onset (mean: 53.4 versus 57.1 years, P = 0.049) and diminished life expectancy (median: 48 versus 60 months, P = 0.029). Variations in more than one gene were detected in 16.7% of the patients, supporting the theory of oligogenic basis for ALS. After adjusting for age at onset, increased risk of mortality was associated with males [hazard ratio = 1.740, 95% confidence interval (CI) = 1.105-2.740] and rare genetic variations (hazard ratio = 1.533, 95% CI = 1.001-2.350). Furthermore, bulbar onset (hazard ratio = 1.75, 95% CI = 1.11-2.75) was found to be a negative prognostic factor for survival. Our study provides valuable insights into the genetic complexity and its impact on clinical outcomes in ALS patients of North Indian origin.