Chromosome 15, fibrillin locus but lots of different mutations.  Not linked to collagen genes, despite clinical overlap with Ehlers-Danlos etc.

Neonatal cases can occur, always severe, with cardiac abnormalities and contractures.

Clinical diagnosis – Beighton (he of benign hypermobility score fame) published Berlin criteria, later came Ghent criteria –

• family history important, else
• involvement of the skeleton, plus
• at least 2 other systems, with a minimum of 1 major manifestation (ectopia lentis, aortic dilatation/dissection, or dural ectasia). 

Skeletal – Tall, disproportionate arm span (>1.05x height – 8cm wider than tall at 160cm) and digits, anterior chest deformity, hypermobility (joint laxity), scoliosis/lordosis, high arched palate and crowded teeth.

Eyes – Myopia, corneal flatness, subluxation of lens (ectopia lentis).

Cardiac – MVP, MR, AR and aortic root dilatation (chart of normal measurements available).  Cardiac examination is often normal despite abnormal echo findings! Aortic aneurysm and dissection can be life threatening.

Pulmonary blebs affect some people, recurrent pneumothorax.  Dural ectasia (widening of lumbosacral spinal canal) on CT is very common, hence why a major manifestation, although symptoms unusual.

Life expectancy is reduced, particularly in males. [Omim]