HLA antigens in alkaptonuric patients

Background. In alkaptonuric patients a disabilitating ochronotic arthropath y develops, due to the deposit of a pigmented polymer of homogentisic acid. Since in inherited diseases the clinical expressions may be multifactorial , involving genetic and environmental factors, where the HLA system may pla y a role, we studied HLA antigens in ochronotic patients. Methods. The study was carried out in 21 members of three families of six o chronotic patients and in two isolated ochronotic patients. The HLA typing has been done testing for antigens from loci A, B and C, by international s tandard microlymphocytotoxicity method, and for loci DR and DQ, by fluoresc ence method on immunologically isolated cells by means of antibody-coated m icrospheres. The chi (2) test was used for statistical analysis, with Yates correction due to the low number of observations. Results. Despite the limited number of subjects, due to the rarity of the d isease, a significantly higher prevalence of HLA-DR7 antigen was found in t he alkaptonuric patients when compared to a general population (p <0.02), s uggesting a possible association, while the prevalence of HLA A, B, C and D Q showed no significant differences. Conclusions. It might play a role in t he pathophysiology and in the clinical expression of the disease.