Diagnosis: Familial amyotrophic lateral sclerosis
• Amyotrophic lateral sclerosis (ALS) is a progressive, late-onset motor neuron disease caused by selective premature degeneration and death of upper and lower motor neurons in the motor cortex, brain stem, and spinal cord.
• The disease starts in adult life, typically between 50 and 60 years of age.
• The ensuing progressive paralysis is typically fatal within 3 to 5 years of clinical onset, usually as a result of failure of the respiratory system.
• ALS is one of the more prevalent adult-onset neurodegenerative diseases, with an incidence of 1 to 2 per 100,000 in most populations. The incidence is much higher in the Pacific island of Guam and the Kii Peninsula of Japan, possibly because of consumption of an environmental toxin, β-methylamino-L-alanine.
• The cause of ALS is unknown in most cases, and these cases are referred to as sporadic ALS (SALS).
• Approximately 10% of ALS cases are inherited in a dominant manner and are referred to as familial ALS (FALS).
• To date, mutations in 12 genes have been reported to cause FALS. Among these, SOD1 mutations, which are transmitted in a dominant fashion, account for approximately 20% of all familial ALS forms and about 2% of all ALS cases.
