Characterization of the class I HLA 9.2-kb Pvu II restriction fragment length polymorphism. Linkage to HLA-A and lack of disease association

The strongest reported association between a class I HLA allele and disease is that of HLA-B27 with ankylosing spondylitis (AS). However, it has not been shown whether B27 is the gene that predisposes to the development of AS or if it is merely linked with the disease-susceptibility locus. Furthermore, if B27 itself is the disease-susceptibility gene, there may be epistatic loci that also contribute to the development of AS or modify its clinical manifestation. A class I HLA 9.2-kb Pvu II restriction fragment was recently identified, which, when present in a B27-positive individual, further increased the relative risk for developing AS (from 119 to 297). This study was therefore designed to confirm the association between AS and this restriction fragment length polymorphism (RFLP) and to map the location of this fragment in the genome. The data presented here suggest that the class I HLA 9.2-kb Pvu II RFLP represents a Pvu II polymorphism at the 5' end of the HLA-A locus that is tightly linked with both HLA-A3 and A9 alleles. However, there is no association between this RFLP and AS in a population of patients living in Baltimore.