ACTA ENDOCRINOLOGICA (BUC)

Context. Autoimmune thyroid disease is considered a multifactorial disorder in which autoimmunity against thyroid antigens is facilitated by exposure to endogenous and environmental factors. We present here a rare case of identical female twins who developed consecutively Graves’ disease within a few months and had three HLA susceptibility alleles for the development of Graves’ disease. Subjects. A 28-year-old woman was referred to our hospital complaining of thirst, sweating, palpitations, tremor and skin rash. Laboratory data showed hyperthyroidism with antibodies against the thyroid stimulating hormone receptor and ultrasonography of the thyroid revealed enlargement with hypervascularity. Her identical twin was referred to our hospital because of similar symptoms. Result. We diagnosed them with Graves’ disease and both were treated with methimazole. Human leukocyte antigen genotyping showed that both twins possessed the DRB1*04:05, DQB1*04:01:01, DPB1*05:01 haplotype, which confers susceptibility to Graves’ disease. Conclusions. This case supports the hypothesis that interaction of multiple human leukocyte antigen susceptibility alleles as well as genetic background and environmental factors might synergistically contribute the close timing in Graves’ disease onset.