Review: clinical variability and genetic heterogeneity in multiple epiphyseal dysplasia.

This review reports on multiple epiphyseal dysplasia (MED), first described clinically in the early part of the 20th century. Over 50 years later, we are now beginning to unravel the mystery behind the genetic mutations involved in triggering the changes in cartilage observed in this condition. In the past decade considerable progress has been made in identifying the underlying genetic defect in some forms of MED. Understanding the precise effect that these molecular changes have on the integrity of the cartilage extracellular matrix will lead the way in identifying the complex disease pathophysiology that defines MED. In addition, a greater understanding of the role and interactions of specific cartilage molecules may reveal the basis of more widespread cartilage disorders such as osteoarthritis.