HLA-B*27 IS STRONGLY ASSOCIATED IN MEXICAN MESTIZOS WITH ACUTE ANTERIOR UVEITIS WITH NO ADDITIONAL CONTRIBUTION OF CLASS II GENES

HLA-B*27 IS STRONGLY ASSOCIATED IN MEXICAN MESTIZOS WITH ACUTE ANTERIOR UVEITIS WITH NO ADDITIONAL CONTRIBUTION OF CLASS II GENES.
C. Alaez1, L Arellanes2, MN Vazquez-Garcia1,3, G de la Rosa1, B Ibarrola1, P Navarro2, C Espinosa2, C. Gorodezky.1 1Dept. of Immunogenetics, INDRE, SSA..2 Inflammatory Eye Disease Clinic. APEC. 3 PMBM-CINVESTAV Mexico City, MEXICO.

Acute Anterior Uveitis (AAU) is the most common form of intraocular inflammation; it is characterized by iritis or iridocyclitis. A single episode does not cause permanent visual loss, but the recurrent nature of the disease results in loss of vision. More than half of AAU patients in different countries are HLA-B27, and half of them have associated spondyloarthropathy. The cause of these disease is unknown, but B27 is responsible for at least 25% of the etiology, while other genes and exogenous factors are the cause for the remaining 75%. AAU comprises 75% of all uveitis seen at the Mexican Referral Center. The aim of this work was to analyze the contribution of class I and/or class II genes to susceptibility to the disease in Mexicans. We studied 102 patients, and 170 healthy individuals all of them Mexican Mestizos. HLA-A, B, C analysis was performed by microlymphocytotoxicity using double fluorescence staining. DNA typing of DRB1, DQA1 and DQB1 alleles was done by PCR-SSOP according to the protocols of 12th IHW. The subtyping of B*27 was performed by PCR-SSP. Of the total patients, 64.1% were males. HLA-B*27 was found increased when compared with the controls (OR=51.3, p=2.3E-24), but the subtype distribution did not differ between patients and controls. The most frequent allele in both groups is B*2705, which is the ancestral allele. The results of class II analysis showed an association with DRB1*0101, (OR=4.4, pc=0.01). To distinguish between the contribution of B27 and DRB1*0101, a stratification analysis was done in the presence and absence of both alleles. The results demonstrated that DRB1*0101 and B*2705 are in linkage disequilibrium in both groups with no particular contribution of DRB1 locus to the etiology of AAU, indicating that the participation of MHC genes is restricted to HLA-B or to class I linked regions.