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Osteogenesis imperfecta collagen defect — MRCPCH TAS MCQ

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HardPathologyOsteogenesis imperfecta collagen defectMRCPCH TAS

A newborn has multiple fractures at different stages of healing, blue sclerae and a family history of brittle bones. Biochemical tests for calcium and phosphate are normal. What is the most likely molecular abnormality?

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Correct answer: C — Type I collagen defect

Osteogenesis imperfecta is usually due to quantitative or qualitative defects in type I collagen, producing bone fragility and blue sclerae. Fibrillin-1 defects cause Marfan syndrome rather than brittle bones with normal mineral biochemistry. The pearl is that inherited bone fragility must be considered when fractures are otherwise unexplained.

Reference: Nelson Textbook of Pediatrics; RCPCH Theory examination syllabi; Lissauer's Illustrated Textbook of Paediatrics