Early Spondyloarthritis in an HLA-B27-positive Monozygotic Twin Pair: A Highly Concordant Onset, Sites of Involvement, and Disease Course

Excerpt

To the Editor:

Susceptibility to ankylosing spondylitis (AS) and the related spondyloarthropathies (SpA) is determined by a strong polygenetic predisposition interacting with as-yet unknown environmental factors. HLA-B27 is one of the major disease susceptibility genes, and studies of HLA-B27-positive twins have shown a concordance rate of 63% among monozygotic versus 24% in dizygotic twin pairs^1–5. Making an early diagnosis of AS and related SpA is often challenging, and there are no validated diagnostic criteria^6–10. Magnetic resonance imaging (MRI) is the imaging method of choice for early detection and assessment of inflammatory lesions in the axial skeleton prior to…