For amyotrophic lateral sclerosis (ALS), Wakisaka et al. knocked down Cabeza (Caz, a Drosophila homologue of FUS, which is one of the genes causing ALS in humans) in Drosophila to examine the role of Aub, a PIWI responsible for piRNA biogenesis, in neural disorders [141]. The gene discussed is PIWIL4; the disease is amyotrophic lateral sclerosis.