Below is an instruction from Human. Write a response.
    ### Instruction:
    What causes Amyotrophic lateral sclerosis ?
    ### Response:
    What causes amyotrophic lateral sclerosis? In approximately 90-95% of cases the cause of amyotrophic lateral sclerosis (ALS) is unknown and is sporadic (occurring in individuals with no history of the condition in the family). The remaining 5-10% of cases are genetic (familial), often occurring in individuals with a family history of the condition.
    