Autoimmune polyendocrinopathy type 3 (APS3) is an autoimmune condition that affects the body's endocrine glands. The syndrome, which typically affects women during middle age, results from failure of the glands to produce their hormones. This condition is characterized by autoimmune thyroiditis along with another organ-specific autoimmune disease. The other autoimmune diseases may include diabetes mellitus, pernicious anemia, vitiligo, alopecia, myasthenia gravis, and Sjogren's syndrome. The adrenal cortex (the outer layer of the adrenal gland) is not involved. There are three types of autoimmune polyendocrinopathy type 3: APS3A - Autoimmune thyroiditis with immune-mediated diabetes mellitus (IMDM), APS3B - Autoimmune thyroiditis with pernicious anemia, APS3C - Autoimmune thyroiditis with vitiligo and/or alopecia and/or other organ-specific autoimmune disease. The cause is still unknown, but it is believed that it may be an autoimmune disease, where environmental factors (such as viral infections) and genetic factors (such as variations in the HLA II genes) are also involved in the disease. In many cases more than one member of the same family is affected with PAS III, suggesting that its inheritance could be autosomal dominant, and therefore, familiar screening is recommended. It is very important that people with APS3 are monitored closely by their doctors for early detection of any glandular problems.