Clinical and demographic details of subjects. ALS, amyotrophic lateral sclerosis; n, Number; M, male; F, female; y, years; mo, months; B, bulbar; L, limb; Age, age of onset, duration of disease are indicated as mean ± standard deviation (SD). † Unpaired, independent 2-tailed student t test analysis showed that mean age differ significantly among the groups (p = 0.004). ‡ Duration of disease is the interval between appearance of first symptom of ALS and collection of sample. ALS subjects were asked to provide all clinical and demographic details at the age of disease-onset.