ANKYLOSING SPONDYLITIS AND KLINEFELTER'S SYNDROME: DOES THE X CHROMOSOME MODIFY DISEASE EXPRESSION?

Abstract

ANKYLOSING spondylitis has attracted special attention in rheumatology because of its very strong association with HLA-B27 and because it is one of the few relatively-common rheumatic diseases which is characterized by a male predominance. Males are also affected more severely (1) and this accounts, at least in part, for the tendency to late diagnosis in females. None of the theories concerning aetiopathogenesis provides a satisfactory explanation for this male predominance. It has been suggested that a gene on the Y chromosome may contribute to disease susceptibility (2). We describe a man with ankylosing spondylitis and Klinefelter's syndrome whose father also has ankylosing spondylitis. However, the radiographic features of the son differ from those of the father and conform more to those described in female spondylitics. This rare coincidence invites speculation as to the origin of the sex differences noted in this condition. We suggest that the X chromosome may be important in determining disease expression.