Sphingolipids are hydrolyzed by ceramidases to yield sphingosine and fatty acids. These ceramidases are classified according to the pH range that supports their optimal activity. ASAH1 is an acid ceramidase and key regulator of ceramide metabolism. Mutations in this gene results in Farber Lipogranulomatosis, a fatal human genetic disorder that results in the painful swelling of the joints and tendons and pulminary insufficiency, while a complete knockout of its expression is lethal in mice. Recent studies have shown elevated levels of ASAH1 in Alzheimer's disease (AD) patients correlating with a reduction in sphingomyelin and elevation of ceramide. Pretreatment of cultured neurons with recombinant AHAH1 prevented the cells from undergoing A-beta (Ab)-induced apoptosis. Multiple isoforms of this protein are known to exist.Synonyms: ASAH, ASAH1, Acylsphingosine deacylase, N-acylsphingosine amidohydrolase, PHP32, Putative 32 kDa heart protein