Interestingly, a study conducted in 2021 proposed the association of variants in serine palmitoyltransferase, long-chain base subunit 1 (SPTLC1) with juvenile ALS (namely ALS4), but not with adult-onset ALS, and implicated sphingolipid metabolism as a pathway in motor neuron disease [58]. The gene discussed is SPTLC1; the disease is amyotrophic lateral sclerosis type 2, juvenile.