Arrested epidermal morphogenesis in three newborn infants with a fatal genetic disorder (restrictive dermopathy)

Progeroid syndrome patients with ZMPSTE24 deficiency could benefit when treated with rapamycin and dimethylsulfoxide

Patients with progeroid syndromes such as mandibuloacral dysplasia, type B (MADB) and restrictive dermopathy (RD) harbor mutations in zinc metalloproteinase (ZMPSTE24), an enzyme essential for posttranslational proteolysis of prelamin A to form mature lamin A. Dermal fibroblasts from these patients show increased nuclear dysmorphology and reduced proliferation; however, the efficacy of various pharmacological agents in reversing these cellular phenotypes remains unknown. In this study, fibroblasts from MADB patients exhibited marked nuclear abnormalities and reduced proliferation that improved upon treatment with rapamycin and dimethylsulfoxide but not with other agents, including farnesyl transferase inhibitors. Surprisingly, fibroblasts from an RD patient with a homozygous null mutation in ZMPSTE24, resulting in exclusive accumulation of prelamin A with no lamin A on immunoblotting of cellular lysate, exhibited few nuclear abnormalities and near-normal cellular proliferation. An unbiased proteomic analysis of the cellular lysate from RD fibroblasts revealed a lack of processing of vimentin, a cytoskeletal protein. Interestingly, the assembly of the vimentin microfibrils in MADB fibroblasts improved with rapamycin and dimethylsulfoxide. We conclude that rapamycin and dimethylsulfoxide are beneficial for improving nuclear morphology and cell proliferation of MADB fibroblasts. Data from a single RD patient's fibroblasts also suggest that prelamin A accumulation by itself might not be detrimental and requires additional alterations at the cellular level to manifest the phenotype.

Embryonic expression of the common progeroid lamin A splice mutation arrests postnatal skin development

Hutchinson-Gilford progeria syndrome (HGPS) and restrictive dermopathy (RD) are two laminopathies caused by mutations leading to cellular accumulation of prelamin A or one of its truncated forms, progerin. One proposed mechanism for the more severe symptoms in patients with RD compared with HGPS is that higher levels of farnesylated lamin A are produced in RD. Here, we show evidence in support of that hypothesis. Overexpression of the most common progeroid lamin A mutation (LMNA c.1824C>T, p.G608G) during skin development results in a severe phenotype, characterized by dry scaly skin. At postnatal day 5 (PD5), progeroid animals showed a hyperplastic epidermis, disorganized sebaceous glands and an acute inflammatory dermal response, also involving the hypodermal fat layer. PD5 animals also showed an upregulation of multiple inflammatory response genes and an activated NF-kB target pathway. Careful analysis of the interfollicular epidermis showed aberrant expression of the lamin B receptor (LBR) in the suprabasal layer. Prolonged expression of LBR, in 14.06% of the cells, likely contributes to the observed arrest of skin development, clearly evident at PD4 when the skin had developed into single-layer epithelium in the wild-type animals while progeroid animals still had the multilayered appearance typical for skin at PD3. Suprabasal cells expressing LBR showed altered DNA distribution, suggesting the induction of gene expression changes. Despite the formation of a functional epidermal barrier and proven functionality of the gap junctions, progeroid animals displayed a greater rate of water loss as compared with wild-type littermates and died within the first two postnatal weeks.

Restrictive dermopathy: a rare laminopathy

BACKGROUND

Restrictive dermopathy (RD) belongs to the laminopathies and mostly shows an autosomal recessive heredity pattern. This rare genetic disorder is lethal for the newborn in the neonatal period. Clinical and pathological findings are distinctive and allow for a specific diagnosis in most cases. Furthermore, polyhydramnios, decreased foetal movement, facial dysmorphisms and arthrogryposis are characteristic of RD. Respiratory insufficiency leads to an early neonatal death.

METHODS

We present the case of an affected infant and a review of the previously reported cases in the literature.

RESULTS

The infant showed thin, shiny skin with exfoliating desquamation, a small, round and open mouth, low-set ears, a small pinched nose, joint contractures at all four extremities and distinctive pulmonic atelectasis. It died 3 h and 20 min post-partum. Histologically, the skin showed the typical pattern of an RD with the epidermis covered by an exfoliated, hyperkeratotic horn layer, clearly hypoplastic hair follicles and a considerably reduced dermis thickness, although it had a massive subcutaneous adipose tissue. Electron microscopically, the diagnosis was confirmed.

CONCLUSIONS

It is important to know about this disease and to distinguish it from others like keratinization malfunctions such as ichtyosis, congenital, developmental and akinesia disturbance, etc., to know the prognosis for the affected newborn and to provide sufficient (genetic) counselling to the families. This disorder is caused by dominant mutations of the LMNA (primary laminopathy) or recessive mutations of the ZMPSTE24 (FACE1) (secondary laminopathy) genes.

Restrictive dermopathy: report and review

Restrictive dermopathy is a rare autosomal recessive disorder characterized by extreme tautness of the skin causing restricted intrauterine movement and a fetal akinesia deformation sequence. It is uniformly mostly neonatally fatal. The diagnostic findings are skin tautness with near absence of the dermal elastic fibers, usually with no or only minor anomalies of the internal organs. The exact pathogenetic mechanisms are still not known. Fewer than 50 cases have been reported. We report on a case of restrictive dermopathy and discuss the differential diagnoses.

Disturbed Epidermal Structure in Mice with Temporally Controlled Fatp4 Deficiency

So far, little is known about the physiological role of fatty acid transport protein 4 (Fatp4, Slc27a4). Mice with a targeted disruption of the Fatp4 gene display features of a human neonatally lethal restrictive dermopathy with a hyperproliferative hyperkeratosis, a disturbed epidermal barrier, a flat dermal-epidermal junction, a reduced number of pilo-sebaceous structures, and a compact dermis, demonstrating that Fatp4 is necessary for the formation of the epidermal barrier. Because Fatp4 is widely expressed, it is unclear whether intrinsic Fatp4 deficiency in the epidermis alone can cause changes in the epidermal structure or whether the abnormalities observed are secondary to the loss of Fatp4 in other organs. To evaluate the functional role of Fatp4 in the skin, we generated a mouse line with Fatp4 deficiency inducible in the epidermis. Mice with epidermal keratinocyte-specific Fatp4 deficiency developed a hyperproliferative hyperkeratosis with a disturbed epidermal barrier. These changes resemble the histological abnormalities in the epidermis of newborn mice with total Fatp4 deficiency. We conclude that Fatp4 in epidermal keratinocytes is essential for the maintenance of a normal epidermal structure.

Sealing the live part of the skin: the integrated meshwork of desmosomes, tight junctions and curvilinear ridge structures in the cells of the uppermost granular layer of the human epidermis

In the literature the question of whether a system structurally and functionally related to the barrier function of the tight junctions (TJs) of polarized epithelia exists in the epidermis has been and still is controversially discussed. We have systematically addressed this question in a study of the granular layer of fetal and adult human epidermis, combining different light and electron microscopic methods. We show that the lateral membranes of the cells of the stratum granulosum are connected by an extended subapical complex system integrating desmosomes and TJ structures identified as sites of close membrane-membrane contact and as regions of membrane-to-membrane apposition that in immunoelectron microscopy are positive for TJ marker proteins, notably occludin, indicative of an extended, probably continuous TJ barrier. In addition, we have noted in freeze-fractures of the apical membrane attaching this layer to the basalmost membrane of the stratum corneum an extended system integrating desmosomes with intramembraneous ridge configurations that appear as strands, circles, lariats or complex meshworks showing numerous continuities with the desmosomes. In some regions this system interconnecting desmosomes with curvilinear ridge structures occupies the major part of the plasma membrane. The molecular organizations and possible functional contributions of both structural systems positioned at the border between the living portion of the epidermis and the corneal layer are discussed, in particular in relation to the formation of a stable association between the two layers and of a barrier to the paracellular flow of molecules and particles. It is also discussed whether similar structures occur in other keratinizing stratified squamous epithelia, in squamous metaplasias and in tumors derived from such tissues.

Mice with targeted disruption of the fatty acid transport protein 4 (Fatp 4, Slc27a4) gene show features of lethal restrictive dermopathy

The fatty acid transport protein family is a group of evolutionarily conserved proteins that are involved in the cellular uptake and metabolism of long and very long chain fatty acids. However, little is known about their respective physiological roles. To analyze the functional significance of fatty acid transport protein 4 (Fatp4, Slc27a4), we generated mice with a targeted disruption of the Fatp4 gene. Fatp4-null mice displayed features of a neonatally lethal restrictive dermopathy. Their skin was characterized by hyperproliferative hyperkeratosis with a disturbed epidermal barrier, a flat dermal-epidermal junction, a reduced number of pilo-sebaceous structures, and a compact dermis. The rigid skin consistency resulted in an altered body shape with facial dysmorphia, generalized joint flexion contractures, and impaired movement including suckling and breathing deficiencies. Lipid analysis demonstrated a disturbed fatty acid composition of epidermal ceramides, in particular a decrease in the C26:0 and C26:0-OH fatty acid substitutes. These findings reveal a previously unknown, essential function of Fatp4 in the formation of the epidermal barrier.

Restrictive dermopathy: a case report and a critical review of all hypotheses of its origin

Restrictive dermopathy (RD) is a rare, fatal, autosomal recessive genodermatosis in which tautness of a translucent thin skin is the major clinical observation. This causes an intrauterine fetal akinesia deformation sequence (FADS) resulting in polyhydramnios, reduced fetal movements at around 31 weeks gestation, dysmorphic facies, arthrogryposis, and early neonatal death because of respiratory insufficiency. The characteristic histologic abnormalities of the skin are located in a thin dermis, consisting of compactly arranged collagen fibers, scant elastic fibers, and poorly developed skin appendages. The epidermal rete ridges are flattened and the dermal-hypodermal border is remarkably straight. The etiology of these changes remains unclear. We tested several existing hypotheses and could not confirm them. These included fibroblast dysfunction, abnormal keratin composition, desmosomal changes, and increased proinflammatory cytokines [tumor necrosis factor (TNF)-alpha and interleukin (IL)-6]. We conclude that RD is a relatively easy clinical and pathologic diagnosis, but that the pathogenesis of the disease is not clarified.

Restrictive dermopathy and fetal behaviour

We report three siblings from consecutive pregnancies affected with restrictive dermopathy (RD). During the second pregnancy, fetal behavioural development and growth were studied extensively using ultrasound at 1-4 week intervals. Dramatic and sudden changes occurred in fetal body movements and growth but not until the end of the second trimester of pregnancy. Prominent at that time were prolonged periods of fetal quiescence and very low heart rate variability, together with abnormally executed body movements of short duration. Retarded femoral development and jerky abrupt fetal body movements (abnormal movement quality) were already present in the early second trimester of pregnancy. Facial anomalies emerged despite the presence of fetal mouth movements. The clinical features of RD were only partly explained by present knowledge of skin development and the fetal akinesia deformation sequence hypothesis. Quantitative assessment of fetal movements proved to be a poor early marker for antenatal diagnosis of this disorder.

Immunohistochemical localization of transforming growth factor-alpha and epithelial growth factor receptor in human fetal developing skin, psoriasis and restrictive dermopathy

Keratinocytes release a number of cytokines interacting with other intra- and subepidermal cells during the initiation and the perpetuation of skin inflammatory reactions. Cultured human keratinocytes overexpressing the transforming growth factor alpha (TGF-alpha) assumed a spindled morphology and displayed increased locomotion. Moreover, the receptor for TGF-alpha, the epithelial growth factor receptor (EGFR), is important for autocrine growth, promotion of cell survival, and regulation of cell migration. The expression of TGF-alpha and EGFR has not been widely studied in human developing skin and their roles in geno-dermatosis are not known. In this study, we investigated the expression of TGF-alpha and EGFR by immunohistochemistry in human developing skin at different gestational ages (14 th week, 20 th week, and 34 th week), in six patients with psoriasis, and, for the first time, in an infant affected with restrictive dermopathy, a very rare lethal genodermatosis, characterized by abnormal skin growth and differentiation with thin, tightly adherent skin. TGF-alpha and EGFR were expressed in the basal layer at the 14 th week and in all epidermal layers at the 20 th and 34 th week of gestation. In psoriasis, TGF-alpha was overexpressed in all layers of epidermis, while EGFR was expressed in the basal and first suprabasal layers. In restrictive dermopathy, we observed no expression of both TGF-alpha and EGFR at the level of the skin. The other organs showed comparable patterns to those of an age-matched infant. In conclusion, TGF-alpha and EGFR interact strictly to promote skin development during the intrauterine life. An interactive autocrine growth cycle between TGF-alpha and EGFR is present in psoriasis. A skin-localized alteration of the expression of TGF-alpha and EGFR may be at the basis of restrictive dermopathy. The delay of growth and differentiation of the skin in restrictive dermopathy may be related to the absent expression of TGF-alpha, which is probably due to a down regulation of EGFR by an abnormal autocrine mechanism.

Restrictive dermopathy: report of a case and review of the literature

BACKGROUND

Restrictive dermopathy is a rare autosomal recessive skin disorder that is fatal in the neonatal period. Clinical and pathologic findings are distinctive and allow for a specific diagnosis in most cases.

METHODS

We present a case of an affected infant and a review of the previously reported cases in the literature.

RESULTS

The infant had thick shiny skin with reduced compliance and multiple spontaneous linear splits. Additional findings included an abnormal facies with a distinctive small, round and open mouth, low set ears, small nose, widely spaced sutures, flexion contractures of the extremities, and poorly expanded lungs. The infant expired 65 h after birth. Histologic findings of the skin at autopsy included a relatively unremarkable epidermis, a flat dermal-epidermal junction (absent rete ridges), an overall thinned dermis with hypoplastic appendage structures, a dense fibrotic reticular dermis with collagen parallel to the epidermis, a sharp subcutaneous margin, and an abnormally thick layer of subcutaneous adipose tissue. Electron microscopic findings included dense dermal patches of collagen and fibroblasts with abundant endoplasmic reticulum and unusually small tonofilaments. Review of previously reported cases reveals strikingly consistent findings.

CONCLUSIONS

This rare condition illustrates that abnormal cutaneous development may produce fetal hypokinesia, leading to profound effects on intrauterine growth and development. The autosomal recessive pattern of inheritance and morphologic changes of the skin and skeletal system in this disorder suggest that a structural protein or enzyme defect, perhaps of collagen metabolism, may underlie the pathogenesis.

Lipid and ultrastructural characterization of reconstructed skin models

The study aimed at evaluating tissue architecture and quality of the permeability barrier in commercially available reconstructed human skin models; EpiDerm, SkinEthic and Episkin in comparison to native tissue. For this purpose, tissue architecture was examined by electron microscopy and epidermal lipid composition was analyzed by HPTLC. Stratum corneum lipid organization was investigated by electron microscopy in combination with RuO(4) post-fixation and by SAXD. Ultrastructurally, the overall tissue architecture showed high similarities with native epidermis. In the stratum corneum extracellular space, lipid lamellae consisting of multiple alternating electron-dense and electron-lucent bands were present. This regular pattern was not seen throughout the whole stratum corneum probably due to the observed irregular lamellar body extrusion in some areas. Lipid analyses revealed the presence of all major epidermal lipid classes. Compared with native epidermis the content of polar ceramides 5 and 6 was lower, ceramide 7 was absent, and the content of free fatty acids was very low. These differences in lipid composition may account for differences observed in SAXD pattern of Episkin and EpiDerm penetration models. In the latter only the long-distance periodicity unit of about 12 nm was observed and the short periodicity unit was missing. In conclusion, all three skin models provide a promising means for studying the effects of topically applied chemicals, although the observed deviations in tissue homeostasis and barrier properties need to be optimized.

Cyclic ichthyosis with epidermolytic hyperkeratosis: A phenotype conferred by mutations in the 2B domain of keratin K1

Bullous congenital ichthyosiform erythroderma (BCIE) is characterized by blistering and erythroderma in infancy and by erythroderma and ichthyosis thereafter. Epidermolytic hyperkeratosis is a hallmark feature of light and electron microscopy. Here we report on four individuals from two families with a unique clinical disorder with histological findings of epidermolytic hyperkeratosis. Manifesting erythema and superficial erosions at birth, which improved during the first few months of life, affected individuals later developed palmoplantar hyperkeratosis with patchy erythema and scale elsewhere on the body. Three affected individuals exhibit dramatic episodic flares of annular, polycyclic erythematous plaques with scale, which coalesce to involve most of the body surface. The flares last weeks to months. In the interim periods the skin may be normal, except for palmoplantar hyperkeratosis. Abnormal keratin-filament aggregates were observed in suprabasal keratinocytes from both probands, suggesting that the causative mutation might reside in keratin K1 or keratin K10. In one proband, sequencing of K1 revealed a heterozygous mutation, 1436T-->C, predicting a change of isoleucine to threonine in the highly conserved helix-termination motif. In the second family, a heterozygous mutation, 1435A-->T, was found in K1, predicting an isoleucine-to-phenylalanine substitution in the same codon. Both mutations were excluded in both a control population and all unaffected family members tested. These findings reveal that a clinical phenotype distinct from classic BCIE but with similar histology can result from K1 mutations and that mutations at this codon give rise to a clinically unique condition.

Restrictive dermopathy: report and review

Restrictive dermopathy (RD) is a lethal autosomal recessive genodermatosis (MIM No. 275210) in which tautness of the skin causes fetal akinesia or hypokinesia deformation sequence (FADS). Polyhydramnios with reduced fetal movements is followed by premature delivery at around 31 weeks gestation. Manifestations include a tightly adherent, thin, translucent skin with prominent vessels, typical facial changes, generalized joint contractures, enlarged fontanelles, dysplasia of clavicles, respiratory insufficiency, and an enlarged placenta with short umbilical cord. Histologic abnormalities of the skin include thin dermis with paucity and hypoplasia of the appendages and abnormally arranged collagen bundles. Elastic fibers are nearly missing. The subcutaneous fat is slightly increased. These skin findings usually appear after 22 or 24 weeks of gestation, which is why prenatal diagnosis with skin biopsy may fail. This disease is easily differentiated from other congenital FADS, such as Pena-Shokeir syndrome, COFS syndrome, Parana hard-skin syndrome, etc. We report on an affected boy of consanguineous parents and 30 previous cases are reviewed.

Restrictive dermopathy: a disorder of skin differentiation with abnormal integrin expression

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.

Prenatal detection of epidermolysis bullosa letalis with pyloric atresia in a fetus by abnormal ultrasound and elevated alpha-fetoprotein

We report on the prenatal diagnosis of epidermolysis bullosa letalis with pyloric atresia in a pregnancy not known to be at risk for this condition. Elevated maternal serum alpha-fetoprotein levels led to ultrasonography which demonstrated gastric dilatation, consistent with pyloric atresia, and echogenic particles in the amniotic fluid, the "snowflake sign," previously described in two pregnancies of fetuses with disorders of skin sloughing. Amniotic fluid alpha-fetoprotein was markedly elevated and the acetylcholinesterase was positive. The diagnosis of epidermolysis bullosa letalis with pyloric atresia was confirmed after delivery by electron microscopy of fetal skin which showed typical changes of hypoplastic absent hemidesmosomes and separation along the dermal-epidermal junction. None of these abnormal prenatal findings are consistently present in pregnancies with epidermolysis bullosa with pyloric atresia. Thus, although useful when abnormal, when the test results are normal, the need for confirmatory fetoscopy and fetal skin biopsy remains.

Restrictive dermopathy: a lethal congenital skin disorder

Restrictive dermopathy is a recently described lethal congenital disorder of the skin with an autosomal recessive mode of inheritance. The rigidity of the skin impairs fetal movements in utero and causes arthrogryposis, as well as highly characteristic facial features and pulmonary hypoplasia. We report two cases of restrictive dermopathy in prematurely born infants, describe the typical pathological findings and discuss this disorder in the context of the fetal akinesia/hypokinesia deformation sequence.

False-negative prenatal diagnosis of restrictive dermopathy

Restrictive dermopathy is a rare autosomal recessive lethal skin dysplasia. It has been assumed that the characteristic morphologic abnormalities should allow a reliable prenatal diagnosis on fetal skin biopsies at about 20 weeks pregnancy. We report on a false-negative prenatal diagnosis.

Restrictive dermopathy: a disorder of fibroblasts

Restrictive dermopathy is a rare, lethal genodermatosis, characterized by a thin, tightly adherent skin which causes a dysmorphic facies, arthrogryposis and respiratory insufficiency. The recorded cases to date show a remarkable phenotypic similarity. Thinning of the dermis and the arrangement of collagen in parallel bundles appear to be constant findings. We have found many dead and degenerating fibroblasts in the dermis on ultrastructural examination, and have demonstrated their poor growth in vitro. Studies of collagen from a skin sample showed a marked increase in mature cross-links, indicating a decrease in skin collagen turnover. These findings suggest a primary disorder of fibroblasts, and may explain the apparent arrest in growth and differentiation of the skin which appears to be important in the pathogenesis of this rare condition.

Dermatopathological aspects of restrictive dermopathy

We present an immunopathological and electronmicroscopic study of the skin of two newborns affected by restrictive dermopathy. Evidence of abnormal maturation was found in the epidermis, cutaneous appendages, dermis, and hypodermis. Our observations confirm two previous descriptions. We emphasize some unreported data concerning the L1 antigen and Factor XIIIa in the skin. The L1 antigen is expressed in the interadnexal epidermis, but not in hair follicles. This is the reverse pattern compared with normal skin. Factor XIIIa is poorly expressed in dermal dendrocytes, which appear rare compared with controls. The multiple defects in maturation found in all cutaneous tissues suggest a qualitative or quantitative aberration in control mechanisms of tissue interactions.

Restrictive dermopathy, a lethal form of arthrogryposis multiplex with skin and bone dysplasias: three new cases and review of the literature

Restrictive dermopathy is a rare, lethal autosomal recessive syndrome. We report on 3 unrelated affected stillborn infants of consanguineous parents. Clinical findings include a tight, thin, translucent, taut skin, which tears spontaneously in flexion creases, arthrogryposis multiplex congenita (including the temporomandibular joint), enlarged fontanelles, typical face and dysplasia of clavicles and long bones. Histologic abnormalities include hyperplastic, abnormally keratinized epidermis, reduced tonofilaments, thin, compact dermis with hypoplasia of the elastic fibres, and abnormal subcutaneous fat. Fifteen previous cases are reviewed.

Epidermal growth factor receptors in genetically induced hyperproliferative skin disorders

The presence and morphologic distribution of epidermal growth factor receptor (EGF-R) were investigated in a variety of genetic disorders that affect human epidermis. These diseases included various forms of ichthyoses as well as restrictive dermopathy and the CHILD syndrome (congenital hemidysplasia-ichthyosiform erythroderma-limb defects). The distribution of EGF-R was detected by immunohistochemical techniques. Increased staining of immunoreactive EGF-R was frequently, but not always, seen in lesions with experimental or clinical evidence of hyperproliferation, suggesting an increased potential to respond to endogenous levels of either transforming growth factor-alpha or EGF. The finding that EGF-R levels are not always increased in congenital epidermal disorders indicated that the presence of this receptor pathway is not simply a marker for aberrant epidermis.

Hereditary palmoplantar keratosis of the Gamborg Nielsen type. Clinical and ultrastructural characteristics of a new type of autosomal recessive palmoplantar keratosis

A new kind of diffuse palmoplantar keratoderma with autosomal recessive inheritance and without associated symptoms was described in Norrbotten, Sweden by Gamborg Nielsen in 1985. Clinically, it ranges between the less severe dominant Unna-Thost type and the more severe recessive Meleda type, as it is milder than the latter. Skin biopsies of five patients from three different families with this new palmoplantar keratoderma, as well as five obligatory heterozygotes from one family, were investigated ultrastructurally in order to characterize this new entity and to differentiate it from the Meleda type. Several features are common to both autosomal recessive palmoplantar keratoses. They show a broadened granular layer, a transit region consisting of cells with a marginal envelope, and considerable hyperkeratosis. Morphologically, this transformation delay is less pronounced in the Gamborg Nielsen type than in the classical Meleda type. As is typical for ridged skin, both types of palmoplantar keratoses possess composite keratohyaline granules. In contrast to the normal appearance of keratohyaline granules in the Meleda type, the Gamborg Nielsen type also shows qualitative deviations of keratohyaline granules with different degrees of spongiosity and electron density and sometimes with a granular border. It seems that abnormal keratohyaline proteins are synthesized that behave differently. The sudden transformation of a granular into a horny cell is physiologically regulated by different enzymes. A delay in this process may be caused by a mutation that reduces or alters the enzymes concerned. We assume the palmoplantar keratoderma of the Gamborg Nielsen type to be a variant of the heterogeneous group of the Meleda type of palmoplantar keratoderma with autosomal recessive inheritance.

Restrictive dermopathy with distinct morphological abnormalities

A newborn child is described with the fetal hypokinesia sequence as a consequence of a restrictive dermopathy. Remarkable findings in this infant were neonatal teeth and survival till age 4 months. Ultrastructural examination of the skin showed thin epidermis and absence of elastic fibres.

Restrictive dermopathy: a report of three cases

We report three infants with a rare syndrome of restrictive dermopathy, in which rigidity of the skin at birth is associated with characteristic facial anomalies, generalised arthrogryposis, bony abnormalities, and lung hypoplasia. The skin has a distinctive pathology with compaction of the dermal collagen and fibrosis of the subcutaneous tissue. The inheritance is likely to be autosomal recessive and the condition appears to be fatal in the early neonatal period.

Heterogeneity in harlequin ichthyosis, an inborn error of epidermal keratinization: variable morphology and structural protein expression and a defect in lamellar granules

Skin biopsies and scale samples from nine infants and one fetus affected with harlequin ichthyosis (HI) were obtained from eight families. Epidermal differentiation was examined by morphologic and biochemical criteria and cell culture studies. Two striking abnormalities were identified; first, keratin and filaggrin expression were abnormal and varied between cases, and, second, in all cases lamellar granules were absent or abnormal, and intercellular lamellae within the stratum corneum were absent. Three HI phenotypes were distinguished by variable expression of epidermal structural proteins. Cases were classified by the absence (type 1) or presence (types 2 and 3) of keratins K6 and K16 ("hyperproliferative" keratins) and by the presence of profilaggrin in the interfollicular epidermis (types 1 and 2 only). Profilaggrin is apparently not converted to filaggrin, but it is retained in the scale. The block in profilaggrin processing may be due to an inactive phosphatase. Siblings in two families (presenting with types 1 and 2) showed the same type classification suggesting that expression of the phenotype is consistent within families but differs between families. Cultured HI keratinocytes were normal by phase microscopy, but abnormal by electron microscopy with no lamellar granules and extensive stacking of the upper layers. We conclude that harlequin ichthyosis is a genetically heterogeneous group of disorders with altered lamellar granules, intercellular lipids, and variation in expression and/or processing of structural protein markers of normal epidermal keratinization. Furthermore, the lamellar granule and structural protein defects may be indirectly related via a mechanism involving phosphorylation/dephosphorylation.