Identifying heritable connective tissue disorders in childhood.

Heritable connective tissue diseases are rare. Each disorder estimated at 1-10 per 100,000. However, as a group they are prevalent enough to constitute an important diagnostic challenge. Connective tissue disorders most significantly affect three systems: musculoskeletal, ocular and cardiovascular. The cardinal feature of the majority of these disorders is ligamentous laxity, or joint hypermobility. The joints show an increased range of movement, and the child may present with arthralgias, effusions and an increased risk of joint or soft tissue injury. Marfan syndrome is the most common heritable connective tissue disorder. It is an autosomal dominant condition with high penetrance but with striking pleiomorphism. In 25% of individuals there is no family history. The diagnosis is often not made until late childhood. Individuals are tall with a low upper: lower segment ratio and an arm span greater than height. Other skeletal characteristics include pectus deformity and scoliosis. Myopia and astigmatism are common. Cardiac abnormalities include mitral valve prolapse, mitral regurgitation and arrhythmias. Early diagnosis, meticulous echocardiographic follow-up and multidisciplinary assessment are essential. The Ehlers-Danlos syndromes share a triad of features: skin hyperextensibility, articular hypermobility, and tissue fragility. The abnormalities are caused by genetic defects resulting in the faulty synthesis or structure of collagen. There is a wide variety of phenotypes and mode of inheritance. Symptom management and joint protection are important to improve quality of life and prevent secondary complications. Osteogenesis imperfecta encompasses a group of rare heritable disorders associated with low bone mass and increased susceptibility to fractures. Increased bone fractures after minimal trauma is the cardinal feature. Other features include blue sclera, hearing loss, scoliosis, deafness, and hypermobility.