Human SLE and other autoimmune diseases also are likely to be highly complex genetically. Interestingly, there may be some overlap genetically between different forms of autoimmune disease, such as SLE and type I diabetes. More than half of the linkages identified in genomewide scanning studies of a variety of systemic and organ-specific autoimmune diseases map nonrandomly into eighteen chromosomal clusters, possibly explaining the occurence of several autoimmune diseases in a given individual or family. For example, Hashimoto’s thyroiditis is associated with a variety of organ-specific (eg TID, pernicious anemia, autoimmune hepatitis, and Addison’s disease) and systemic (eg lupus, RA and sjogren syndrome) autoimmune diseases. Pedigrees with more than one systemic autoimmune disorders are not unusual. Of course, shared environmental influences could also explain familial clustering.