A brother and sister from consecutive pregnancies had rigid and tightly adherent skin in association with generalized contractures, unusual facies, pulmonary hypoplasia, an abnormal placenta, and a short umbilical cord. Both died shortly after birth. Pathologic examination of the skin by light and electron microscopy showed structural abnormalities of the epidermis, dermis, and subcutaneous fat. An abnormal pattern of keratin proteins was determined biochemically using extracted epidermal proteins. Autopsy showed a normal spinal cord and muscle histology. It is postulated that the defective skin severely restricted movement and secondarily led to the other abnormalities. Familial occurrence is most consistent with autosomal recessive transmission. These patients and the primary skin defect are discussed within the framework of the Fetal Akinesia or Hypokinesia Deformation Sequence.

We studied several members of a family with an X-linked form of cutis laxa; the affected males have mild skin laxity, a characteristic facies, skeletal abnormalities, structural abnormalities of the genitourinary tract, and low serum copper levels. The activity of lysyl oxidase, a copper-dependent enzyme involved in cross-link formation in collagen, was decreased in skin-biopsy specimens (13 to 26 per cent of normal) and in culture medium from cells to two affected males (15 to 20 per cent of normal). Immunoreactive lysyl oxidase from skin of both patients was virtually undetectable by immunodiffusion assay. The amounts of lysyl-derived aldehydes (the product formed in collagen and elastin by lysyl oxidase) and of cross-links formed from these products were decreased in dermal fibroblasts in culture. Collagen extractability from these cells was increased in culture. These findings suggest that lysyl oxidase deficiency provides the biochemical basis of the X-linked form of cutis laxa.

Repeated epilation (Er) is a radiation-induced, autosomal, incomplete dominant mutation in mice which is expressed in heterozygotes but is lethal in the homozygous condition . Many effects of the mutation occur in skin : the epidermis in Er/Er mice is adhesive (oral and nasal orifices fuse, limbs adhere to the body wall), hyperplastic, and fails to undergo terminal differentiation. Skin from fetal +/+, Er/+ and Er/Er mice at ages pre-and postkeratinization examined by light, scanning, and transmission electron microscopy showed marked abnormalities in tissue architecture, differentiation, and cell structure; light and dark basal epidermal cells were separated by wide intercellular spaces, joined by few desmosomes, and contained phagolysosomes . The numbers of spinous, granular, and superficial layers were highly variable within any given region and among various regions of the body. In some areas, 2-8 layers of granular cells, containing large or diminutive keratohyalin granules, extended to the epidermal surface; in others, the granular layers were covered by several layers of partially keratinized or nonkeratinized cells. In rare instances, a single or small group of cornified cells was present among the granular layers but was not associated with the epidermal surface. Both the granular and non keratinized/partially keratinized upper epidermal layers in Er/Er skin gave positive immunofluorescence with antiserum to the histidine-rich, basic protein, filaggrin. Proteins in epidermal extracts from +/+, Er/+ and Er/Er mice were separated and identified by radio-and immunolabeling techniques . The Er/Er extract was missing a 26 .5-kdalton protein and had an altered ratio of bands in the keratin region . The 26 .5-kdalton band was histidinerich and cross-reacted with the antiserum to rat filaggrin. Several high molecular weight bands present in both Er/Er and +/+ extracts also reacted with the antiserum . These are presumed to be the precursors of filaggrin and to account for the immunofluorescence in Er/Er epidermis even though the product protein is absent . The morphologic and biochemical data indicated that the genetic defect has a general and profound influence on epidermal differentiation, including alteration of two proteins (filaggrin and keratin) important in normal terminal differentiation, tissue architecture, and cytology . Identification of epidermal abnormalities at early stages of development (prekeratinization) and defective structure of other tissues and gross anatomy suggest that the mutation is responsible for a defect in some regulatory step important in many processes of differentiation and development.

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