What is the definition or description of: hla b27?

Tissue type at B: Hla = human leukocyte antigen. Important in recognition of self and not self. Different proteins (antigens) for different people. B is one of the loci, and hlab27 has been associated with predisposition to immunologic rheumatologic diseases, especially ankylosing spondylitis.

See details: The hla system is a found on the number 6 autosomal chromosome. You are b27 positive if the number 27 gene is present at the b site in this system. This gene is associated with a number of arthritic conditions.