ASAH1 and arthritic joint disease: ASAH1/Asah1 defect and the resulting excess tissue accumulation of Cer affect joint tissues, liver, heart, kidneys, lymph nodes, and central nervous system and are characterized by the symptoms of painful swelling of joints, arthritis, subcutaneous nodules, and hoarseness by laryngeal involvement, hepatosplenomegaly, nervous system dysfunction, and the increased lethargy and sleepiness [27,28,172].