Biochemical characteristics of Ehlers-Danlos syndrome type VI in a family with one affected infant.

The parents of a child with the clinical symptoms of Ehlers-Danlos syndrome type VI were identified as third-degree cousins. Biochemical analysis of the dermis of the patient revealed a complete lack of hydroxylysine in the dermal collagen. The dermis of both parents contained only half the amount of hydroxylysine found in healthy individuals. Hydroxylation of prolyl residues was normal in the skin of the patient and his parents. Investigation of the collagen synthesized by fibroblasts derived from the skin of the patient showed a normal proportion of type I and type III collagen. However, while hydroxylation of prolyl residues was normal in type I and type III collagen, hydroxylation of lysyl residues was markedly lower than normal in both type I and type III collagen.