Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0043346 (xeroderma pigmentosum)
 2,924 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Xeroderma pigmentosum is a very rare precancerous skin disease that is triggered by sunlight. It is caused by a defect in the DNA repair system and causes benign and malignant transformations. Only eye tissues that come into contact with UV light are affected, such as the lids, conjunctiva and cornea. We describe a patient who suffered from xeroderma pigmentosum type C, showing the typical skin alterations but no sign of malignancy. A perforating keratoplasty was performed on both eyes because of the dense opacity of the corneas. The corneal buttons obtained were examined by light and transmission electron microscopy. Degeneration was found only in the basal-cell layer of the corneal epithelium. The most severe morphological changes were seen in Bowman's layer, the subepithelial stroma, Descemet's membrane and the corneal epithelium. Bowman's layer was often interrupted or replaced by a degenerative pannus, which extended into the underlaying stroma. Subepithelial "channels" were localized in the basal epithelium and protruded into the subepithelial stroma. In both corneas, Descemet's membrane contained different amounts of so-called lattice collagen, and the remaining endothelial cells in the left cornea contained numerous melanin granules.
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PMID:Histology and transmission electron microscopy of the cornea in xeroderma pigmentosum type C. 191 29

Ataxia-telangiectasia and xeroderma pigmentosum are human hereditary diseases in which patients are cancer prone and demonstrate increased sensitivity to DNA damage by ionizing and ultraviolet radiation, respectively. In culture, both ataxia-telangiectasia and xeroderma pigmentosum skin fibroblasts show increased synthesis and secretion of the extracellular matrix proteins fibronectin and collagen. To determine whether these differences in protein production result from fundamental abnormalities in regulation of genes associated with cellular interactions, we compared the effects of trifluoperazine and 12-O-tetradecanoylphorbol-13-acetate on expression of the extracellular matrix-degrading metalloproteinases, procollagenase and prostromelysin, by normal, ataxia-telangiectasia, and xeroderma pigmentosum fibroblasts. After trifluoperazine treatment the overall levels of these metalloproteinases were much greater in three ataxia-telangiectasia cell strains and in cells from xeroderma pigmentosum complementation groups A and D than in normal cells. In contrast, cells from xeroderma pigmentosum complementation group C produced only slightly more procollagenase than normal cells. 12-O-tetradecanoylphorbol-13-acetate also induced higher than normal levels of procollagenase in some ataxia-telangiectasia and xeroderma pigmentosum strains, but less than that induced by trifluoperazine. Because increased extracellular accumulation of matrix-degrading enzymes has long been implicated in metastatic progression, this altered expression of procollagenase and prostromelysin in ataxia-telangiectasia and xeroderma pigmentosum cells could play an important role in the pathogenesis of various tumors in individuals with these genetic diseases.
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PMID:Enhanced expression of procollagenase in ataxia-telangiectasia and xeroderma pigmentosum fibroblasts. 217 6

We describe the clinical features and findings of biopsied sural nerves of 4 cases of xeroderma pigmentosum. Nine genetic forms of xeroderma pigmentosum have been reported by complementation studies. These four cases were diagnosed as Group A xeroderma pigmentosum by complementation studies using cultured skin fibroblasts. All cases had delayed mental and motor development in areas such as head control over 4 months of age and walking without support over 18 months of age. Three cases had the gradual onset of a gait disturbance between 6 and 9 years of age. Motor conduction velocity and sensory conduction velocity of the ulnar nerve were slightly delayed. The sural nerve of the slightly impaired patient showed a normal density of myelinated fibers, but a selective reduction of the large myelinated fibers with zebra-body-like structures in Schwann cell cytoplasm. The population density of all nerve fibers was severely diminished in the severely impaired cases. Ultrastructural observation disclosed many denervated Schwann cells and pockets of collagen isolated by loops of denervated Schwann cell cytoplasm. These findings suggest that the degenerative process in peripheral nerves of xeroderma pigmentosum is axonal. Peripheral neuropathy in Group A xeroderma pigmentosum resembles that of patients with ataxia telangiectasia who are known to have a defect in the repair mechanisms of their DNA in cultured skin fibroblasts.
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PMID:Peripheral neuropathy in four cases of group A xeroderma pigmentosum. 283 98

The sural nerves of 2 siblings, 7 and 6 years of age with Group A xeroderma pigmentosum, were biopsied. The densities of myelinated fibers, 5,808/mm2 and 5,163/mm2, respectively, were strikingly decreased in comparison to control data. Both large and small myelinated fibers were reduced. Electron microscopy demonstrated many collagen fibers in the endoneurium and some collagen pockets. The loss of myelinated fibers was less severe than in previously reported patients. This discrepancy may be due to age differences at biopsy; our patients were biopsied at the ages of 7 and 6 years, while those patients reported previously were 10 years of age or older. The incidence of neurologic manifestations in xeroderma pigmentosum may increase after 6 years of age.
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PMID:Quantitative histologic study of sural nerves in xeroderma pigmentosum. 350 84

A clinical and neuropathological study of a case of xeroderma pigmentosum with severe neurological abnormalities was performed. The patient developed sensitivity to the sun, followed by freckles and malignant skin tumors. Some years after the onset of the cutaneous symptoms, a slowly progressive mental deterioration was noted. Subsequently, dysarthria, increased sensitivity and a tendency to cry and to be easily frightened developed together with ataxia and spasticity of the limbs. Late in the course of the disease the patient was severely disabled because of spastic tetraplegia. The clinical examination revealed generalized slowing in EEG, mixed sensory and motor neuropathy in EMG, thick skull, both cerebral cortical atrophy and ventricular dilatation in computed tomography and marked decrease in cerebrospinal homovanillic acid content. The neuropathological study showed marked loss of neurons in the basal nucleus of Meynert, the substantia nigra, the cerebellum, medulla and spinal cord. Diffuse loss of neurons was noted in the cerebral cortex and in the deep cerebral nuclei. In the nerve cells, a high amount of cytoplasmic lipofuscin was observed in some areas of CNS. The sciatic nerve showed marked loss of axons and heavy deposition of collagen around the remaining nerve fibers. The present neuropathological findings explain many of the clinical symptoms observed in xeroderma pigmentosum and show similarities with those observed in olivopontocerebellar atrophy, although the basic mechanism for the CNS damage is still unclear.
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PMID:Xeroderma pigmentosum with neurological abnormalities. A clinical and neuropathological study. 370 28

Xeroderma pigmentosum (XP) is an autosomal recessive disorder characterized by severe sun-sensitivity, early skin cancers and abnormal DNA repair. XP has a worldwide distribution with an approximate frequency of 1/250,000. It is classified into nine complementation groups, and distribution of patients among the various groups is related to ethnic origin. To our knowledge, the association of XP with thrombasthenia has not been reported previously; here a 12-year-old girl with this combination is reported. She was first noted to have skin erythema on exposure to sunlight at the age of six months and was diagnosed with XP. At the age of one she had the complaints of easy bruising and epistaxis. A diagnosis of thrombasthenia was made based on the absence of platelet aggregation response to ADP, collagen and adrenaline and reduced clot retraction. In clinical management, oral isotretinoin was given in order to suppress tumor formation.
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PMID:Association of xeroderma pigmentosum with thrombasthenia. 870 96

Some rare hereditary syndromes demonstrate high cancer risk and hypersensitivity in response to exposures to agents such as ultraviolet or ionising radiation, and are characterised by a defective processing of DNA damage. They highlight the importance of the individual capacity of restoring the genomic integrity in the individual risk associated to exposures. The comet assay, a simple technique that detects DNA strand breaks, requires few cells and allows examination of DNA repair capacities in established cell lines, in blood samples or biopsies. The assay has been validated on cellular systems with known repair defects such as xeroderma pigmentosum defective in nucleotide excision repair, on mutant rodent cell lines defective in DNA single strand break rejoining (XRCC1) (alkaline version) or DNA double strand breaks rejoining (XRCC5/Ku80 and XRCC7/DNAPKcs) (neutral conditions). This assay does not allow to distinguish a defective phenotype in ataxia telangiectasia cells. It shows in homozygous mouse embryo fibroblasts Brca2-/- an impaired DNA double strand break rejoining. Simplicity, rapidity and sensitivity of the alkaline comet assay allow to examine the response of lymphocytes. It has been applied to the analysis of the role of DNA repair in the pathogenesis of collagen diseases, and the involvement of individual DNA repair proficiency in the thyroid tumorigenesis induced in some patients after therapeutic irradiation at childhood has been questioned. Preliminary results of these studies suggest that this type of approach could help for adapting treatment modalities and surveillance in subgroups of patients defective in DNA repair process. It could also have some incidence in the radioprotection field.
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PMID:[Individual radiosensitivity and DNA repair proficiency: the value of the comet assay]. 986 98

Cockayne syndrome (CS) and xeroderma pigmentosum (XP) are caused by deficient nucleotide excision repair. CS is characterized by cachectic dwarfism, mental disability, microcephaly and progeria features. Neuropathological examination of CS patients reveals dysmyelination and basal ganglia calcification. In addition, arteriosclerosis in the brain and subdural hemorrhage have been reported in a few CS cases. Herein, we performed elastica van Gieson (EVG) staining and immunohistochemistry for collagen type IV, CD34 and aquaporin 4 to evaluate the brain vessels in autopsy cases of CS, XP group A (XP-A) and controls. Small arteries without arteriosclerosis in the subarachnoid space had increased in CS cases but not in either XP-A cases or controls. In addition, string vessels (twisted capillaries) in the cerebral white matter and increased density of CD34-immunoreactive vessels were observed in CS cases. Immunohistochemistry findings for aquaporin 4 indicated no pathological changes in either CS or XP-A cases. Hence, the increased subarachnoid artery space may have caused subdural hemorrhage. Since such vascular changes were not observed in XP-A cases, the increased density of vessels in CS cases was not caused by brain atrophy. Hence, brain vascular changes may be involved in neurological disturbances in CS.
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PMID:Brain vascular changes in Cockayne syndrome. 2174 65

Sirtuins are a family of seven proteins in humans (SIRT1-SIRT7) that are involved in multiple cellular processes relevant to dermatology. The role of sirtuins in other organ systems is established. However, the importance of these proteins in dermatology is less defined. Recently, sirtuins gained international attention because of their role as "longevity proteins" that may extend and enhance human life. Sirtuins function in the cell via histone deacetylase and/or adenosine diphosphate ribosyltransferase enzymatic activity that target histone and non-histone substrates, including transcription regulators, tumor suppressors, structural proteins, DNA repair proteins, cell signaling proteins, transport proteins, and enzymes. Sirtuins are involved in cellular pathways related to skin structure and function, including aging, ultraviolet-induced photoaging, inflammation, epigenetics, cancer, and a variety of cellular functions including cell cycle, DNA repair and proliferation. This review highlights sirtuin-related cellular pathways, therapeutics and pharmacological targets in atopic dermatitis, bullous dermatoses, collagen vascular disorders, psoriasis, systemic lupus erythematosus, hypertrophic and keloid scars, cutaneous infections, and non-melanoma and melanoma skin cancer. Also discussed is the role of sirtuins in the following genodermatoses: ataxia telangiectasia, Cowden's syndrome, dyskeratosis congenita, Rubenstein-Taybi, Werner syndrome, and xeroderma pigmentosum. The pathophysiology of these inherited diseases is not well understood, and sirtuin-related processes represent potential therapeutic targets for diseases lacking suitable alternative treatments. The goal of this review is to bring attention to the dermatology community, physicians, and scientists, the importance of sirtuins in dermatology and provide a foundation and impetus for future discussion, research and pharmacologic discovery.
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PMID:Sirtuins in dermatology: applications for future research and therapeutics. 2337 38

Mutations in the XPD subunit of the DNA repair/transcription factor TFIIH result in distinct clinical entities, including the cancer-prone xeroderma pigmentosum (XP) and the multisystem disorder trichothiodystrophy (TTD), which share only cutaneous photosensitivity. Gene-expression profiles of primary dermal fibroblasts revealed overexpression of matrix metalloproteinase 1 (MMP-1), the gene encoding the metalloproteinase that degrades the interstitial collagens of the extracellular matrix (ECM), in TTD patients mutated in XPD compared with their healthy parents. The defect is observed in TTD and not in XP and is specific for fibroblasts, which are the main producers of dermal ECM. MMP-1 transcriptional up-regulation in TTD is caused by an erroneous signaling mediated by retinoic acid receptors on the MMP-1 promoter and leads to hypersecretion of active MMP-1 enzyme and degradation of collagen type I in the ECM of cell/tissue systems and TTD patient skin. In agreement with the well-known role of ECM in eliciting signaling events controlling cell behavior and tissue homeostasis, ECM alterations in TTD were shown to impact on the migration and wound-healing properties of patient dermal fibroblasts. The presence of a specific inhibitor of MMP activity was sufficient to restore normal cell migration, thus providing a potential approach for therapeutic strategies. This study highlights the relevance of ECM anomalies in TTD pathogenesis and in the phenotypic differences between TTD and XP.
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PMID:TFIIH-dependent MMP-1 overexpression in trichothiodystrophy leads to extracellular matrix alterations in patient skin. 2560 38


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