A Heritable Disorder of Connective Tissue

TLDR

Two sisters with severe scoliosis, recurrent joint dislocations, and hyperextensible skin and joints illustrate a connective tissue disorder. Dermal collagen from the affected sisters shows markedly reduced hydroxylysine, increased solubility, and normal morphology, while parents and a clinically normal sister have normal collagen; the defect is likely autosomal recessive and due to deficient lysine hydroxylation, compromising collagen integrity.

Abstract

Two sisters nine and 12 years of age presented with a similar clinical picture consisting of severe scoliosis, recurrent joint dislocation and hyperextensible skin and joints. Amino acid analyses of dermal collagen revealed marked decrease in hydroxylysine content; skin from a clinically normal older sister and from the parents was normal in amino acid content. Collagen fibrils were normal morphologically. Dermal collagen from the affected children was more soluble in denaturing solvents than that derived from controls. Hydroxylysine content was also reduced in lumbodorsal fascia, variably reduced in bone and normal in a single sample of costal cartilage. The defect is probably inherited as an autosomal recessive and due to a deficiency of enzymatic hydroxylation of lysine in collagen, which in turn results in decreased structural integrity of this important protein.