By the differential display of genes showing altered expression during senescence in human diploid fibroblasts, Chambers et al. (1998) cloned MOXD1, which they called MOX. DBH-like monooxygenase protein 1, also known as monooxygenase X, is an enzyme that in humans is encoded by the MOXD1 gene. The MOXD1 gene, located on 6q23.2, is conserved in chimpanzee, Rhesus monkey, dog, cow, mouse, rat, chicken, zebrafish, fruit fly, mosquito, and frog. MOXD1 belongs to the copper type II ascorbate-dependent monooxygenase family. 2 alternatively spliced human isoforms have been reported. MOXD1 is widely expressed in the endometrium, adrenal, and other tissues. DBH-like 1 maintains many of the structural features of dopamine beta-monooxygenase DBH. DBH deficiency has been treated effectively with L-Threo-3,4-dihydroxyphenylserine (DOPS).