Association study of MICA-TM and HLA-class I polymorphism with uveitis in South Tunisian population.

Background: Uveitis refers to intraocular inflammation. The pattern of uveitis is largely influenced by a multitude of factors including genetic background.

Aim: The purpose of our study was to identify the association between the polymorphism of the transmembrane region of MICA (MICA-TM) and uveitis in Tunisian patients with intraocular inflammation.

Patients And Methods: A total of 79 Tunisian patients and 123 healthy controls were enrolled in our study. HLA-class I phenotyping was performed by microlymphocytotoxicity complement dependent and MICA-TM was genotyped by a semiautomatic fluorescent-labelled PCR method, amplicons were analysed on ABI Prism 310 genotyper. Comparisons of allele frequencies between patients and controls, and between patients' subgroups were performed using SPSS 20.0.

Results: In our 79 patients, HLA-B27 showed a significant increased frequency when compared with healthy controls (P=0.003, 7.88 [95% IC=2.17-28.65]). The association was more significant when considering idiopathic anterior uveitis (P=0.00002, OR=11.65 [95% IC=3.06-45.17]). No MICA allele was significantly increased in uveitis groups compared to controls. In the idiopathic uveitis group, MICA-A4 was associated with late age of onset of disease (P=0.04). HLA-B51 and MICA-A6 were associated respectively with severe tyndall (P=0.008) and with the presence of synechiae (P=0.007).

Conclusion: Some clinical features of uveitis may be influenced by specific MICA-TM alleles. In our South Tunisian population, MICA plays a disease modifying role, rather than being an important gene in the susceptibility for developing of uveitis.