Autoimmune polyendocrinopathy associated with ring chromosome 18.

Phenotypic and clinical features of individuals with ring chromosome 18 [r(18)] vary with the extent of deletion of the short (18p-) or long arm (18q-). Most patients with r(18), therefore, demonstrate a clinical spectrum of both 18p- and 18q- deletions. Short stature, microcephaly, mental and motor retardation, craniofacial dysmorphism and extremity abnormalities are the most commonly reported features in patients with r(18). Abnormalities of chromosome 18, especially 18p- syndrome, are often reported with autoimmune thyroid disease and growth hormone deficiency, but reports of endocrine abnormalities associated with r(18) are rare. Here, we report a case of an African-American female with hyperthyroidism, type 1 diabetes mellitus, vitiligo and IgA deficiency associated with a r(18) chromosome complement. This patient additionally had mild intellectual disability and dysmorphic features. Karyotype analysis showed a de novo ring chromosome 18 (deletion 18q23-18qter and deletion 18p11.3-18pter). Although this unique association of autoimmune polyglandular endocrinopathy with ring chromosome 18 could be coincidental, we speculate that a gene or genes on chromosome 18 might play a role in the autoimmune process.