Chromosome 18q deletion syndrome with autoimmune diabetes mellitus: putative genomic loci for autoimmunity and immunodeficiency.

A girl with 18q deletion syndrome was diagnosed with autoimmune diabetes mellitus and Hashimoto's thyroiditis at the age of 3 yr. In addition, the girl suffered from recurrent infections due to immunoglobulin A and IgG4 deficiency. She was also found to have CD3+CD4+FoxP3+, CD3+CD4+FoxP3+CD25+, and CD3+CD4+CD25+CD127 regulatory T cells deficiency. The exceptional coincidence of the two autoimmune disorders occurring at an early age, and associated with immune deficiency, implies that genes located on deleted 19.4 Mbp region at 18q21.32-q23 (chr18:58,660,699-78,012,870) might play a role in the pathogenesis of autoimmunity leading to β cell destruction and diabetes.