Unusual facies, thumb hypoplasia, distinctive spinal fusions and extraspinal mobility limitation, in a pair of monozygotic twins.

We report a pair of monozygotic twins with unusual facies and hypoplastic thumbs associated with progressive spinal fusion and joint immobility. The radiographic features were neither consistent with the multiple synostosis syndrome of Herrmann, nor with the spondylocarpotarsal synostosis syndrome. The overall spinal radiographic abnormalities seen in our patients were suggestive of an exceptionally early onset of Forestier disease (anterolateral, perivertebral, ligament ossification), but the thumb hypoplasia and pterygium colli are not seen in that condition. We report what might be a novel genetic entity.