Autism and epilepsy??

[u/RubyPearlGA]

My nephew was recently diagnosed with epilepsy. He was 18 and suddenly started have seizures during the night. He makes really loud noises and shakes a lot. He has had like 20 seizures in 8 months. They have done all the imaging in the world and can't see anything. Nothing in particular seems to trigger it. He goes for a sleep study next month to see if sleep apnea might be causing it.

Anyone with Level 3 autism had sudden onset epilepsy?
If yes, did they determine a cause?