Around 10% of amyotrophic lateral sclerosis (ALS) cases are familial (FALS), with the remainder being sporadic (SALS). Known ALS genes combined (including superoxide dismutase 1, SOD1) only account for about 20% of familial ALS cases, or around 2% of all ALS cases. Frontotemporal dementia (FTD) is estimated to be associated with between 3 and 22% of ALS cases and as many as one half of ALS cases appear to have frontotemporal impairment.1 Families with co-morbid ALS and FTD are increasingly being recognised, and linkage analysis has implicated loci on chromosome 9.1 Combined, this strongly suggests that ALS and FTD share a common pathogenic basis. Indeed, clinical and pathologic overlap has been demonstrated for these disorders.
- motor neuron