The association between polymorphisms of B7 molecules (CD80 and CD86) and Graves' ophthalmopathy in a Taiwanese population

Objective: This study evaluates whether B7 molecules (CD80 and CD86) could be used as genetic markers for the development of Graves' ophthalmopathy (GO).

Design: Cross-sectional study.

Participants: We included 471 patients with Graves' disease (GD; 200 patients with GO and 271 patients without GO) in a Chinese population in Taiwan.

Methods: An endocrinologist with substantial experience in thyroid diseases identified GO. Blood samples were taken for DNA extraction from GD subjects. The gene polymorphism of CD80 and CD86 was genotyped by polymerase chain reaction in each patient.

Main outcome measures: Genotypes of CD80 and CD86 polymorphism.

Results: We found that the frequency of C allele at position rs_9831894 of the CD86 gene is different in patients with GD (with and without GO; chi-square test, P = 0.0017). In addition, the multifactor dimensionality reduction method was used to identify the best gene-gene interaction to predict the risk of GO. We identified an interaction between CD80_rs9289131 and CD86_rs9872483 (sign test, P = 0.0010). Moreover, the G-A haplotype was shown to have a protective effect in the development of ophthalmopathy among patients with GD (odds ratio, 0.63; 95% confidence interval, 0.44-0.90). Moreover, among patients with GO, the patients carrying the G-A haplotype had a lower level of free thyroxine T(4) than those not carrying the G-A haplotype (P = 0.0001).

Conclusions: These results suggest that the polymorphisms of the CD86 gene may be used as genetic markers for making the diagnosis and prognosis of GO. Therefore, GO could be a disease with complex genetic factors, resulting from the existing gene-gene interaction found in the present study.