The disease may not be genetic. Only a small percentage is. My dad has ALS and in his case is not genetic (lucky me). The disease starts and progresses in different paces for different people - my dad has it for almost 7 years and still talks and eats like before. For him, the first thing to go was his arms; now his legs are almost paralyzed as well.
In his case, it probably is associated with the fact that he worked with agrochemicals his whole life, in a time when regulations and PPE where much loosier. He tells stories of taking baths of substances while his dad worked in orchards.
"Organophosphate poisoning is highly lethal as organophosphates, which are commonly found in insecticides and nerve agents, cause irreversible phosphorylation and inactivation of acetylcholinesterase (AChE), leading to neuromuscular disorders via accumulation of acetylcholine in the body."
I don't know what the interest or accessibility of edaravone (Radicava) treatment might be for your dad, but I'd be happy to share my experience with you by email if that is useful - my address is on my HN user page.
Not to be offensive, but is ALS his confirmed diagnosis? I have two family members who were diagnosed with different rare muscle-wasting diseases and have lost most of their arm and leg function over the past decade. Eating/breathing unaffected. They both lived on farms so we’ve always suspected there was a link.
In his case, it probably is associated with the fact that he worked with agrochemicals his whole life, in a time when regulations and PPE where much loosier. He tells stories of taking baths of substances while his dad worked in orchards.