I. Olivieri et al., OSSIFICATION OF THE POSTERIOR LONGITUDINAL LIGAMENT IN ONE OF A PAIR OF IDENTICAL-TWINS CONCORDANT FOR ANKYLOSING-SPONDYLITIS, Clinical rheumatology, 13(2), 1994, pp. 309-311
A pair of identical twins suffering from ankylosing spondylitis is rep
orted. One brother developed an earlier-onset disease and showed ossif
ication of the posterior longitudinal ligament and the flavum ligament
in his cervical spine.