Clinical Characteristics

Patients may present with these features:

  • Craniosynostosis: premature fusion of the sutures of the skull
  • Skeletal muscle hypotonia: decreased muscle tone
  • Intellectual disability
  • Proptosis: protruding eyeballs
  • Dolichocephaly: long head
  • Hypertelorism: widely spaced eyes
  • Myopia: near-sightedness
  • High arched and narrow palate
  • Downslanting palpebral fissures: downward slanting the eye line
  • Retrognathia: a small or retracted lower jaw
  • Arachnodactyly: extreme long and slender fingers
  • Camptodactyly: permanent flexion of one or more finger joints
  • Scoliosis: abnormal curvature of the spine
  • Pectus deformity: inward or outward malformation of the chest bone
  • Joint hypermobility
  • Joint contractures
  • Mitral valve prolapse: bulging of the mitral valve leaflets into the left atrium
  • Aortic dilatation: widening of the aorta

Patients with a genetic variant affecting amino acid 180 (Thr) display a milder morphological phenotype with a marfanoid habitus and no intellectual disability.