HLA antigens inpsoriatic arthritis subtypes ofa Spanish population

HLA-A,B,andCantigens werestudied in104 Spanish patients withpsoriatic arthritis. Different clinical features wereevaluated andthe patients divided intodisease subsets. HLAB17,B27,B16,andCw6 were themost common haplotypes inthetotal group.The HLA-B17/Cw6 haplotype was increased in patients witholigoarthritis. Theincrease of antigen B17correlated witholigoarthritis and spondarthritis, whereas Cw6was more significant inoligoarthritis. Theprevalence ofthe B27/Cwl haplotype was greater inassociation withspondarthritis andwas probably related totheB27.5 subtype linked toCwl.A significantnegative association between theB44/Cw5 haplotype andpsoriatic arthritis was found. Theexistence ofseveral haplotypic factors in thedifferent subsets isdiscussed. Lackofone ormore HLA factors isthought toberesponsible forthedifferent clinical formsofpsoriatic arthritis. Several studies havefoundan association between susceptibility ofpsoriatic arthritis and HLA-B17,B13,B27,B37antigens."' This antigen association seemstobesecondary tothe stronger Cw6association.5 Studies ofdifferent families haveshownthattheHLA genetic factor plays amajor partinthedevelopment of psoriatic arthritis,6 7butits modeofinheritance isatpresentunclear.8 Different HLA class I antigens may belinked topsoriatic arthritis susceptibility indifferent populations, butthe relation between HLA antigens andclinical subsets ofpsoriatic arthritis hasnot been sufficiently investigated. Theaimofthis study wastomap susceptibility geneswithin theHLA ina large sampleofSpanish subjects with psoriatic arthritis using available HLA markers, andtocorrelate theprevalence ofthese markers withsubsets ofdifferent clinical features.