Melanocyte abnormality and destruction, melanin-concentrating hormone (MCH) MCH receptor autoantibodies, the overexpression of MCH, a high level of homocysteine, an increase in catecholamine, free oxygen radicals, cytomegalovirus and stress may be related to the pathogenesis of vitiligo (14,15,16,17,18,19). Here, PMCH is linked to vitiligo.