Types I and III collagens and the activities of prolyl hydroxylase and galactosylhydroxylysyl glucosyltransferase in skin lesions of tuberous sclerosis.

Collagen synthesis and the ratios of collagen types I and III were assayed from the skin lesions of five subjects with tuberous sclerosis. Collagen synthesis, measured by the activities of prolyl hydroxylase and galactosylhydroxylysyl glucosyltransferase, was clearly increased in three angiofibromas of these patients and in one soft tumour of the face, but it was unchanged in shagreen patches. The total collagen content was decreased in angiofibromas, indicating either increased turnover of collagen or an increased amount of cellular or other macromolecular elements in these lesions. The proportions of types I and III collagens, estimated by cyanogenbromide digestion and SDS-gel electrophoresis, were 80-90% and 10-20%, respectively, in all samples except two angiofibromas, in which the relative amount of type III collagen was increased. This may indicate that angiofibromas of tuberous sclerosis are heterogenous with respect to the collagen types they contain, and that there may be disturbed cell growth or collagen synthesis, with individual variation from case to case.