Osteogenesis imperfecta - Genetic musculoskeletal disorders

Osteogenesis imperfecta

Definition

A heterogenous disorder with brittle bones and involvement of other collagen containing connective tissue.

Incidence

1 in 20,000 live births.

Aetiology

Most of the observed phenotypes result from mutations in one of two genes that code for type I collagen precursor proteins (COL1A1 and COL1A2). Blue sclera result from a thinning of the sclera, which allows the colour of the underlying pigmented tissue to be seen.

Clinical features

Features and classification are given in Table 8.4.

Complications

Hearing loss due to otosclerosis. The triad of otosclerosis, blue sclera and brittle bones is termed van der Hoeve’s syndrome.

Management

Multidisciplinary approach involving physiotherapy, occupational therapy and orthopaedic surgery.

·        Gentle nursing of infant to avoid fractures.

·        Prompt splinting of fractures to prevent deformity. Mobilisation to prevent further osteopenia.

·        Correction of deformities if necessary by surgical intervention.

·        New therapies under evaluation include bisphosphonates, growth hormone and bone marrow transplant.

·        Genetic counselling should be offered where appropriate.