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The Ehlers-Danlos syndrome (EDS) is a heterogeneous group of inherited connective tissue disorders characterised by skin hyperextensibility, joint hypermobility, easy bruising, and cutaneous fragility. Nine discrete clinical subtypes have been classified. We have investigated the molecular defect in a patient with clinical features of Ehlers-Danlos syndromes types I/II and VII. Electron microscopy of skin tissue indicated abnormal collagen fibrillogenesis with longitudinal sections showing a marked disruption of fibril packing giving very irregular outlines to transverse sections. Analysis of the collagens produced by cultured fibroblasts showed that the type V collagen had a population of alpha 1 (V) chains shorter than normal. Peptide mapping suggested a deletion within the triple helical domain. RTPCR amplification of mRNA covering the whole of this domain of COL5A1 showed a deletion of 54 bp. Although six Gly-X-Y triplets were lost, the essential triplet amino acid sequence and C-propeptide structure were maintained allowing mutant protein chains to be incorporated into triple helices. Genomic DNA analysis identified a de novo G+3-->T transversion in a 5' splice site of one COL5A1 allele. This mutation is analogous to mutations causing exon skipping in the major collagen genes, COL1A1, COL1A2, and COL3A1, identified in several cases of osteogenesis imperfecta and EDS type IV. These observations support the hypothesis that type V, although quantitatively a minor collagen, has a critical role in the formation of the fibrillar collagen matrix.

The Marfan syndrome has been linked to the FBN1 gene encoding the microfibrillar glycoprotein fibrillin. To date, there have been no descriptions of microfibrillar abnormalities characteristic of this connective tissue disorder, although biochemical analyses have highlighted apparent abnormalities in fibrillin synthesis, secretion and processing. We have conducted a biochemical and ultrastructural investigation of fibrillin expression and assembly by a panel of dermal fibroblast lines from patients with Marfan syndrome and related diseases. The study has highlighted marked differences between cells in terms of secretion and aggregation of newly-synthesised fibrillin. In addition, electron microscopic visualization of fibrillin assemblies has clearly demonstrated for the first time the plethora of microfibrillar abnormalities that underlie this heterogeneous disorder. These data emphasize the molecular complexity that is a feature of the diverse clinical phenotypes exhibited by Marfan patients.

Werner syndrome is a rare, autosomal, recessive condition that is frequently studied as a model of some aspects of human aging, although the behavioral changes that are usually associated with old age are only seen very infrequently. A most striking aspect of the phenotype of Werner syndrome, presumably arising from the same gene defect, is a dramatic shortening of the replicative life-span of dermal fibroblasts in vitro. The finite replicative life-span of human cells in vitro is due to the stochastic loss of replicative ability in a continuously increasing fraction of newborn cells at every generation. Normal human fibroblasts achieve approximately 60 population doublings in culture, while Werner syndrome cells usually only achieve approximately 20 population doublings. We describe an analysis of the replicative ability of fibroblasts from Werner syndrome patients and demonstrate that the cells in these cultures usually exit, apparently irreversibly, from the cell cycle at a faster rate than do normal cells, although they mostly start off with a good replicative ability. We propose that the Werner syndrome gene is a "counting" gene controlling the number of times that human cells are able to divide before terminal differentiation.

Clinical features and histological findings in two sibs who died from restrictive dermopathy in the neonatal period are described. Fibroblasts cultured from a skin biopsy from the second sib and fibroblasts from normal neonatal skin were studied using monoclonal antibodies to visualise integrin subunits by immunocytochemistry. Restrictive dermopathy fibroblasts displayed increased expression of the alpha-1 and alpha-2 subunits of integrin, those responsible for collagen binding. The increase was not matrix dependent. Integrins may play an important role in tissue differentiation, and our findings support the hypothesis that restrictive dermopathy is a disorder of skin differentiation.

Lipoid proteinosis is described in a family of Scottish descent. Chromosome studies performed on five members were normal. Direct immunofluorescence studies performed on skin with anti-collagen antibodies showed an abnormal distribution of collagen within the skin. No abnormality was detected in DNA extracted from lymphocytes taken from five family members, when probed with gene probes to collagen types alpha 1 (I), alpha 2 (I), alpha 1 (III) and alpha 2 (V).

All-trans retinoic acid increased the incorporation of D-[3H]galactose into particulate and soluble glycoproteins in the epidermis of cultured pig skin slices nearly two-fold. Increased incorporation of D-[3H]galactose was not blocked by tunicamycin. This effect was specific for D-[3H]galactose since the incorporation of D-[3H]glucosamine and L-[14C]leucine into epidermal glycoproteins was unaffected by all-trans retinoic acid. All-trans retinoic acid and 13-cis retinoic acid had quantitatively similar effects on D-[3H]galactose incorporation. All-trans retinyl acetate and an aromatic retinoic acid analogue ('Etretinate') were less effective. SDS polyacrylamide gel electrophoresis and fluorography showed increased incorporation of D-[3H]galactose into all epidermal glycoproteins in the presence of all-trans retinoic acid. There was no evidence for synthesis of new glycoproteins such as mucins.

Skin biopsy specimens from 21 patients with Ehlers-Danlos syndrome (EDS) were compared with controls. With two exceptions, the appearance of the dermal collagen and elastic tissue as seen in the two groups was indistinguishable. One example of type 4 EDS contained a dermis composed of fibers that resembled actinically damaged elastic tissue. The single example of type 6 EDS contained particularly thin collagen fibers. The dermal thickness of specimens of EDS was similar to that of controls, although the abnormal-appearing specimen of type 4 EDS was also abnormally thin. Since the other two biopsy specimens of type 4 appeared to be within the range of normal, there may be heterogeneity in this form of EDS.

The major concanavalin A-binding component in urea/deoxycholate/mercaptoethanol extracts of pig skin was a collagenous disulphide-cross-linked glycopolypeptide with an apparent molecular mass of 150 kDa and a pI of 5.5. Antiserum against the electrophoretically purified glycopolypeptide gave strong dermal staining similar to that seen with fluorescent concanavalin A. Immunocytochemical labelling showed prominent labelling of 3-4 nm dermal microfilaments, particularly those associated with dermal blood vessels and mast cells. Immunoblotting with authentic antiserum indicated that the major skin glycopolypeptide was probably identical with collagen-like glycoprotein, the tissue form of the alpha 1/alpha 2 subunits of type VI collagen. This was confirmed by immunoblotting of authentic type VI collagen from pepsin-treated pig skin. Immunoblotting, metabolic labelling with [3H]glucosamine and immune precipitation showed that an immunoreactive collagenous glycopolypeptide was synthesized and secreted by cultured pig skin fibroblasts. The results suggest that type VI collagen is the major concanavalin A-binding component in pig skin.

In vivo skin elasticity was measured on unaffected forearm skin of twenty-five patients with pseudo-xanthoma elasticum and compared with age and sex-matched controls. The elastic modulus was raised in the recessive type I group and reduced in the dominant types I and II groups. No significant difference in skin thickness was found.

Ehlers-Danlos syndrome (EDS) type I was diagnosed in an 18-year-old girl on the basis of marked skin hyperextensibility with generalized loose-jointedness, pigmented paper-tissue scars, and a pronounced tendency to bruising. Her father and one of her sisters showed a similar phenotype. Her mother was normal. Light microscopy of skin biopsies showed large, irregular collagen fibres in the father and daughter, with normal findings in the mother. Electron microscopy of the skin sections revealed a variation in diameter and shape of the collagen fibrils as well as slight dilatation of the rough endoplasmic reticulum of fibroblasts in father and daughter, but normal findings in the mother. Cultured fibroblasts did not show these changes. Measurements of collagen synthesis by fibroblast cultures showed that type III collagen levels were reduced to 50% of normal in the father and daughter, and were normal in the mother. The alpha I (III) proteins had a normal molecular weight, determined by SDS-PAGE electrophoresis. The phenotypes and biochemical results in the family members tested were compatible with autosomal dominant transmission. To our knowledge, this is the first report of a type III collagen deficiency in Ehlers-Danlos syndrome type I. The findings in this family, especially the pronounced bruising tendency, illustrate the heterogeneity within type I EDS.