Association between the bovine major histocompatibility complex and chronic posterior spinal paresis--a form of ankylosing spondylitis--in Holstein bulls.

A highly significant association was found between the bovine MHC class I antigen BoLA-A8 and a form of vertebral osteophytosis/ankylosing spondylitis known as chronic posterior spinal paresis (PSP) in Holstein bulls (P < 0.001). In a population study, restricted to unrelated bulls, BoLA-A8 was significantly associated with PSP (P = 0.0015) with a relative risk of 34.6. In a family study, one PSP bull, BoLA A8/A20, sired 13 offspring. BoLA-A8 was significantly associated with PSP (P = 0.0008). All five PSP sons inherited the A8 allele and the eight healthy sons each inherited the A20 allele. In three other families a complete association of BoLA-A8 and PSP was observed. Lod score analysis, using all available families, indicated a significant linkage between BoLA and PSP (lod score = 6.9). Based on clinical observation, pathology, age/sex predilection, and a strong association with a class I MHC molecule, this inflammatory disease appears analogous to the human condition known as ankylosing spondylitis.