HLA-B27 Is Necessary But Not Sufficient

Abstract

It is discussed why some, but not all HLA-B27-positive persons get disease when triggered by certain infections. The conclusions are that a possible modifying gene may be found on the other HLA haplotype or outside the HLA complex. Given an epidemic infection afflicting a family, it is the possible differences of other environmental factors which may be of interest, not a further description of the infection initially recognized. The familial clustering of disease is based upon modifying genetic factor(s) and/or environmental factor(s) shared by the family members. Timing of the environmental factors may be instrumental. Penetrance of genetic predisposition may also depend on coincidence of randomly occurring environmental factors.

Key Words:

• HLA-B27
• ankylosing spondylitis
• psoriasis
• Reiter's syndrome
• reactive arthritis