Biochemical Abnormalities in Ehlers-Danlos Syndrome

EHLERS-DANLOS syndrome is an uncommon connective-tissue disorder characterized by hypermobility of joints, hyperelasticity of the skin, and a hemorrhagic tendency. A little more than 100 cases have been recorded. The actual incidence is probably significantly greater since many incomplete forms are not diagnosed.¹ It is a heritable disease involving a single gene-determined autosomal trait with low penetrance and variable expression.² The basic defect is unknown, although it is believed to be a disorder involving the collagen of connective tissue. In 1958, Sjoerdsma et al found that a related disorder, the Marfan syndrome, is characterized by an increased excretion of hydroxyproline.³ This has altered the previous view that the basic defect in the Marfan syndrome is in the elastictissue fibrils since hydroxyproline is present almost entirely in collagen. In fact, it is regarded as a "chemical fingerprint" of collagen.⁴ Since the basic defect in Ehlers-Danlos syndrome presumably also involves collagen, the