Osteogenesis imperfecta

Published on 02/04/2015 by admin

Filed under Internal Medicine

Last modified 22/04/2025

Print this page

rate 1 star rate 2 star rate 3 star rate 4 star rate 5 star
Your rating: none, Average: 0 (0 votes)

This article have been viewed 1132 times

235 Osteogenesis imperfecta

Instruction

Look at this patient’s eyes.

Salient features

History

• Ask about previous fractures

• Ask whether or not the condition runs in the family.

Examination

• Blue sclera

• Look for the following signs:

• Hearing loss as a result of otosclerosis
• Signs of old fractures
• Defective dentine formation in the teeth
• Kyphosis and scoliosis (Fig. 235.1)
• Joint hypermobility
• Hernias
• Aortic regurgitation.
image

Fig. 235.1 Lateral (A) and anteroposterior (B) radiographs showing in typical findings in osteogenesis imperfecta: diffuse osteopenia, scoliosis, compression of several cervical vertebral bodies, and a focal kyphosis at the midcervical level.

(With permission from Song, Maher 2007.)

Diagnosis

This patient has blue sclera with abnormalities of skeleton and teeth (lesion) caused by osteogenesis imperfecta tarda (aetiology), and is disabled by the condition (functional status).

Questions

Why is the sclera blue?

Because the choroid pigment is visible.

Mention other conditions in which the sclera is blue

• Marfan syndrome

• Ehlers–Danlos syndrome.

Advanced-level questions

What is the inheritance?

Usually autosomal dominant, although it may be autosomal recessive. The gene defects are in the two genes, COL1A1 or COL1A2, that encode the procollagen chains of type I collagen. Mutant type I collagen results in autosomal dominant osteogenesis imperfecta. Mutations affecting either of two components of the collagen prolyl 3-hydroxylation complex (cartilage-associated protein and prolyl 3-hydroxylase 1) cause the autosomal recessive form with rhizomelia (shortening of proximal segments of upper and lower limbs) and delayed collagen folding (N Engl J Med 2010;362:521–8).

What is the characteristic pathology?

The most characteristic pathology is a primary reduction in bone matrix with secondary mineralization.

What are the clinical types?

The Sillence classification is into four types (I–IV):

I: nearly normal stature, imperfect dentition, blue sclera, fractures of variable number and minimal deformity

II: usually foetuses die in utero or shortly after birth; multiple fractures of ribs and long bones with little mineralization of calvarium and pulmonary hypertension

III (osteogenesis imperfecta congenita, foetal type): stature markedly diminished as a result of multiple fractures and deformity of long bones in utero; blue sclera, imperfect dentition and hearing loss

IV (osteogenesis imperfecta tarda): stature usually reduced, bone deformity and fractures common; sclera bluish to normal; imperfect dentition; may or may not have loss of hearing.

How would you manage this patient?

• Genetic counselling

• Calcium, vitamin D

• Bisphosphonates may improve bone density and growth in children (N Engl J Med 1998;339:947)

• Bone marrow transplantation to correct mesenchymal defect in children (Nat Med 1999;5:309–13).

Related posts:

Default ThumbnailSixth cranial nerve palsy Osteoarthrosis Optic atrophy Default ThumbnailHepatomegaly Carotid artery aneurysm Felty’s syndrome