Showing papers by "John A. McGrath published in 2004"

Clinical and molecular characterization of lipoid proteinosis in Namaqualand, South Africa.

Abstract: Summary Background Lipoid proteinosis (LiP) is a rare autosomal recessive disorder characterized by a hoarse voice, warty skin infiltration and scarring. Mutations within the extracellular matrix protein 1 (ECM1) gene cause LiP. Since the early 1970s it has been recognized that South Africa has one of the largest groups of LiP patients worldwide, suggesting a probable founder effect. As LiP patients present with considerable clinical variability, this group of patients offers a unique opportunity for genotype–phenotype correlation. Objectives To assess the clinical features and the molecular basis of LiP in patients from the Namaqualand area of the Northern Cape province of South Africa and to examine molecular evidence for a founder effect. Subjects and methods The LiP patient cohort consisted of 29 Coloured patients from Namaqualand and a further seven Caucasoid patients from other areas of South Africa. The control group included 100 healthy geographically and ethnically matched individuals from Namaqualand. Samples were collected after informed consent and with ethics committee approval from the University of the Witwatersrand. LiP patients were examined clinically and a structured recording sheet was completed. A brief neurological evaluation was also performed. The LiP founder effect was investigated at the molecular level by ECM1 mutation detection and haplotype analysis. Results The most consistent clinical signs for a diagnosis of LiP in this group were a hoarse voice and thickened sublingual frenulum leading to restricted tongue movement. Homozygosity for a nonsense mutation in exon 7 of the ECM1 gene, Q276X, was identified in all patients (Coloured and Caucasoid). Despite this genetic homogeneity, considerable clinical variability in skin presentation and psychiatric involvement was observed. Haplotype analysis using markers from a 9·98-Mb region around the ECM1 locus confirmed the founder effect with a founder core haplotype, 19-Q276X-12 (ND1-ECM1-D1S2343), in all but four LiP-associated alleles (n = 58). A LiP carrier rate of 1 in 9 was observed among the 100 Namaqualand controls, predicting a LiP incidence of 1 in 324 in this community. Conclusions Although several consistent clinical features in LiP patients homozygous for the Q276X mutation in the ECM1 gene were observed, there remains considerable clinical variability. This suggests the action of genetic and environmental modifiers of disease severity. Strong molecular evidence supports a single founder effect for the high prevalence of LiP in South Africans, both Coloured and Caucasoid.

Development of antigen-specific ELISA for circulating autoantibodies to extracellular matrix protein 1 in lichen sclerosus

Abstract: Lichen sclerosus is a common, acquired chronic inflammatory skin disease of unknown etiology, although circulating autoantibodies to the glycoprotein extracellular matrix protein 1 (ECM1) have been detected in most patients' sera. We have examined the nature of ECM1 epitopes in lichen sclerosus sera, developed an ELISA system for serologic diagnosis, and assessed clinicopathological correlation between ELISA titer and disease. Epitope-mapping studies revealed that lichen sclerosus sera most frequently recognized the distal second tandem repeat domain and carboxyl-terminus of ECM1. We analyzed serum autoantibody reactivity against this immunodominant epitope in 413 individuals (95 subjects with lichen sclerosus, 161 normal control subjects, and 157 subjects with other autoimmune basement membrane or sclerosing diseases). The ELISA assay was highly sensitive; 76 of 95 lichen sclerosus patients (80.0%) exhibited IgG reactivity. It was also highly specific (93.7%) in discriminating between lichen sclerosus and other disease/control sera. Higher anti-ECM1 titers also correlated with more longstanding and refractory disease and cases complicated by squamous cell carcinoma. Furthermore, passive transfer of affinity-purified patient IgG reproduced some histologic and immunopathologic features of lichen sclerosus skin. This new ELISA is valuable for the accurate detection and quantification of anti-ECM1 autoantibodies. Moreover, the values may have clinical significance in patients with lichen sclerosus.

Characterization of IgG autoantibodies to extracellular matrix protein 1 in lichen sclerosus

Abstract: Although the precise aetiology of lichen sclerosus is unknown, evidence for an autoimmune basis to the disorder is emerging. Indeed, circulating IgG autoantibodies to the glycoprotein extracellular matrix protein 1 (ECM1) have been demonstrated in the sera of about 75% of affected individuals. To assess this humoral immune response further, immunoblotting was performed using bacterial recombinant proteins spanning different domains of the ECM1 protein. The aim was to identify autoantibody-reactive sites recognized by 90 lichen sclerosus sera. The subclass distribution of anti-ECM1 IgG autoantibodies was also determined in 54 lichen sclerosus sera. Immunoblotting showed that the IgG autoantibodies from lichen sclerosus patients recognize multiple antigenic reactive sites on the ECM1 protein within both the amino terminus (50/90, 55.6%) and the protein loop cysteine-rich repeat domains (54/90, 60%), although few sera (7/90, 7.8%) had antibodies to the carboxyl terminus of ECM1. IgG subclass analysis revealed that the anti-ECM1 autoantibodies belong predominantly to the IgG(2) subclass (48/54, 88.9%), either IgG(2) alone (28/54, 51.9%) or in combination with one or more other IgG subclasses. No correlation was found between the site(s) of the ECM1 epitopes or the anti-ECM1 IgG profile and any specific clinical parameters. Nevertheless, characterization of anti-ECM1 antibodies does provide further insight into humoral immune responses and understanding disease mechanisms in lichen sclerosus.

Striate palmoplantar keratoderma arising from desmoplakin and desmoglein 1 mutations is associated with contrasting perturbations of desmosomes and the keratin filament network

Abstract: Summary Background Several hereditary human diseases are now known to be caused by distinct mutations in genes encoding various desmosome components. Although the effects of some of these mutant genes have been analysed by targeted disruption experiments in mouse models, little is known about the cell and tissue changes in affected human patients. Objectives To investigate the effects of heterozygous nonsense mutations in desmoplakin (Dp) and desmoglein (Dsg) 1 which cause the autosomal dominant disorder striate palmoplantar keratoderma (SPPK), focusing on changes in desmosome structure and composition and the associated keratin intermediate filament (KIF) network in palm skin, and in cultured keratinocytes generated from the same site. Methods We analysed palm and nonpalm skin sections from four SPPK patients with Dp mutations and one patient with a Dsg1 mutation with respect to tissue and subcellular morphologies, and correlated the in vivo and in vitro findings. Results Using electron microscopy, we found abnormalities of desmosomes and cell–cell adhesion in the suprabasal layers in the epidermis from patients with both Dsg1- and Dp-associated SPPK. These changes were more advanced in skin from patients with Dp mutations. Both Dp and Dsg1 mutations were accompanied by significantly reduced numbers of desmosomes in the suprabasal layers, while decreased desmosome size was evident only in Dsg1-associated SPPK. Confocal microscopy analysis showed marked differences in the expression of keratins and of desmosome components, both between the two types of SPPK, and between SPPK and normal skin. The expression of keratins K5, K14 and K10 was reduced in Dsg1-associated SPPK skin, whereas perinuclear aggregation of keratin filaments was more evident in Dp-associated SPPK. In both types of SPPK upregulation of K16 was pronounced and involucrin labelling was abnormal. Conclusions Mutations in Dp and Dsg1 genes causing SPPK may be associated with perturbations in epidermal differentiation accompanied by a marked disruption of several components of the epidermal scaffold including desmosomes and the KIF network.

Increased risk of squamous cell carcinoma in junctional epidermolysis bullosa.

Abstract: Non-Herlitz junctional epidermolysis bullosa (JEB) is an autosomal recessive genodermatosis characterized by skin fragility and blistering. It is usually caused by mutations in the genes encoding the basement membrane proteins laminin 5 or type XVII collagen. Clinically, impaired wound healing and chronic erosions cause major morbidity in affected patients. Previously it was thought that these individuals, unlike patients with dystrophic EB, did not have an increased risk of developing skin cancer. However, we describe three patients with non-Herlitz JEB (aged 42, 56 and 75 years) who developed cutaneous squamous cell carcinomas (SCCs). The tumours were well-differentiated in two cases, but one patient had multiple primary SCCs that were either well- or moderately differentiated. Most cases of SCC in non-Herlitz JEB described have occurred in those with laminin 5 defects and on the lower limbs. These clinicopathological observations have important implications for the management of patients with this mechanobullous disorder as well as providing further insight into the biology of skin cancer associated with chronic inflammation and scarring.

Progressive osseous heteroplasia resulting from a new mutation in the GNAS1 gene.

Abstract: Summary Progressive osseous heteroplasia (OMIM 166350) is a rare autosomal dominant condition that presents in childhood as dermal ossification and may progress deeper to involve subcutaneous fat and connective tissue. Recently, paternally inherited inactivating mutations in the GNAS1 gene on chromosome 20q13 have been implicated in the pathogenesis, although sporadic cases have also been reported. We report a 9-year-old British Chinese girl with progressive osseous heteroplasia resulting from a de novo missense mutation (W281R) in the GNAS1 gene. She is of small stature (0.4th centile) and started to develop skin lesions at the age of 9 months. These have been confirmed histologically as osteoma cutis. She is of normal intelligence and development and has no dysmorphic features. The GNAS1 gene exhibits imprinting and maternally inherited mutations have previously been shown to result in Albright's hereditary osteodystrophy (OMIM 103580) with pseudohypothyroidism type 1a, whereas paternally inherited mutations result in progressive osseous heteroplasia or the Albright's hereditary osteodystrophy phenotype with pseudopseudohypothyroidism (OMIM 300800). With only nine mutations of the GNAS1 gene reported so far in progressive osseous heteroplasia, this new mutation helps to extend further the genotype–phenotype correlation.

Generalized dystonia and striatal calcifications with lipoid proteinosis.

Abstract: Lipoid proteinosis (LP) is an autosomal recessive disease that typically presents with papular, verrucous, poxlike, or acneiform scars and lesions and hoarseness. LP was recently mapped to the 1q21 locus and shown to result from mutations in the extracellular matrix protein 1 gene (ECM1). Epilepsy, mental retardation, and hippocampal calcifications can occur. The authors describe a patient with generalized dystonia caused by striatal calcifications.

Complete paternal uniparental isodisomy of chromosome 1 resulting in Herlitz junctional epidermolysis bullosa

Abstract: Herlitz junctional epidermolysis bullosa (JEB) is an autosomal recessive mechanobullous disorder that results from loss-of-function mutations in the genes encoding the basement membrane component, laminin 5. Typically, there are frameshift, splice site or nonsense mutations on both alleles of either the LAMA3, LAMB3 or LAMC2 genes, with affected individuals inheriting one mutated allele from each parent. In this report, we describe a patient with Herlitz JEB in whom DNA analysis revealed homozygosity for the recurrent nonsense mutation R635X in LAMB3, located on chromosome 1q32.2. However, screening of parental DNA showed that although the patient's father was a heterozygous carrier of this mutation, the mother's DNA showed only wild-type sequence. Subsequent genotype analysis using 13 microsatellite markers spanning chromosome 1 revealed that the affected child was homozygous for the entire series of markers tested and that all of the alleles originated from the father. These results indicate that the Herlitz JEB phenotype in this patient is due to complete paternal isodisomy of chromosome 1 and reduction to homozygosity of the mutant LAMB3 gene locus. This is the fourth case of uniparental disomy to be described in Herlitz JEB, but it represents the first example of complete paternal isodisomy for chromosome 1 with a pathogenic mutation in the LAMB3 gene. These findings have important implications for mutation screening in JEB and for genetic counselling.

ADULT ectodermal dysplasia syndrome resulting from the missense mutation R298Q in the p63 gene.

Abstract: Summary Several ectodermal dysplasia syndromes have been shown to result from mutations in the gene that encodes the transcription factor p63. We describe an 11-year-old boy, with clinically normal parents, who had a developmental disorder that resembled EEC (ectrodactyly ectodermal dysplasia-clefting) syndrome (OMIM 604292). He had ectrodactyly and missing middle fingers bilaterally, onychodysplasia, hypodontia with missing teeth, hypohidrosis and lacrimal duct obstruction. DNA sequencing disclosed a heterozygous GA substitution at nucleotide 893, that converts an arginine residue (CGA) to glutamine (CAA), the mutation being designated R298Q. This mutation occurs within the DNA-binding domain of p63, and is close to many of the published EEC syndrome mutations. However, R298Q has been described once previously in a large German pedigree, not with EEC syndrome, but another ectodermal dysplasia disorder, ADULT (acro-dermato-ungual-lacrimal-tooth) syndrome (OMIM 103285). Further clinical assessment in our patient revealed that, apart from not having cleft lip and/or palate, he had an exfoliative dermatitis of his hands and feet, and some freckling on his face and shoulders. Collectively, these features support a diagnosis of ADULT syndrome. This study has identified a specific genotype–phenotype correlation in a rare ectodermal dysplasia syndrome and the findings are useful in improving genetic counselling in this family.

Ectodermal dysplasia showing clinical overlap between AEC, Rapp-Hodgkin and CHAND syndromes.

Abstract: The ectodermal dysplasias represent a complex collection of congenital abnormalities of skin, hair, teeth, nail, and sweat gland development, many of which have overlapping clinical features. In this report, we describe a 7-year-old girl, born to clinically normal parents, with ankyloblepharon, cleft lip/palate and hair abnormalities, features resembling the autosomal dominant disorder, ankyloblepharon-ectodermal dysplasia-clefting (AEC) syndrome, which results from mutations in the sterile-alpha motif domain of the gene encoding the transcription factor, p63. However, direct sequencing of the p63 gene in this individual did not reveal any pathogenic sequence variants. Moreover, two of her paternal cousins were discovered to have similar congenital ectodermal anomalies, raising the alternative possibility of an autosomal recessive pattern of inheritance. Furthermore, all affected individuals lacked a history of erosive scalp dermatitis that is usually characteristic of AEC syndrome. Instead, the scalp hair was coarse and wiry. In addition, another atypical feature, hypohidrosis, was present. Collectively, the clinical features also resembled Rapp-Hodgkin syndrome, Bowen-Armstrong syndrome and CHAND syndrome, but did not appear to fit neatly with any one particular disorder. This case highlights the difficulties in trying to classify the ectodermal dysplasia syndromes on clinical features alone.

Translational benefits from research on rare genodermatoses

Abstract: SUMMARY Significant new discoveries about many of the genodermatoses have been made recently through an improved knowledge of the human genome, advances in molecular screening strategies and also through more comprehensive Internet DNA databases. By 2003, over 350 single gene skin disorders had been characterized at a molecular level. These new data provide more detailed information for patients, allow for more accurate diagnoses, and help improve genetic counselling. Other benefits include the feasibility of carrier screening and DNA-based prenatal testing, as well as a platform for devising new treatments, including somatic gene therapy. Research on rare single gene disorders also provides new insight into more common skin conditions. For example, new ideas about photosensitivity are emerging from discoveries of mutations in a novel component of the actin cytoskeleton (kindlin-1) in the rare inherited poikiloderma disorder, Kindler syndrome. Likewise, new clues to understanding disease pathology in lichen sclerosus have been gleaned from the discovery of pathogenic mutations in the skin protein, extracellular matrix protein 1, in the rare sclerosing inherited skin disorder, lipoid proteinosis. Finally, new insight into what can cause exuberant granulation tissue in chronic wounds has been provided by the discovery of specific mutations in the basement membrane protein, laminin 5, in the rare inherited condition, laryngo-onychocutaneous syndrome. It is clear that a precise research focus on the rare genodermatoses is providing practical benefits for sufferers of these disorders, as well as new lessons and ideas about more common acquired skin conditions.

Expression and glycosylation of MUC1 in epidermolysis bullosa-associated and sporadic cutaneous squamous cell carcinomas.

Abstract: Background Cutaneous squamous cell carcinoma (SCC) is particularly problematic in certain patient groups, including patients with dystrophic or junctional epidermolysis bullosa (DEB/JEB). Theoretically, vaccination against a cell surface antigen which is expressed on this type of tumour could prevent SCC development, as well as treat primary and metastatic disease in this patient group. Preliminary studies have suggested that MUC1, a transmembrane glycoprotein, is overexpressed in sporadic cutaneous SCCs, and MUC1 has been used with some success as a target antigen for vaccine development in breast cancer, where it is expressed on > 50% of neoplastic cells in approximately 50–80% of tumours. Furthermore, aberrant glycosylation of MUC1 has been detected in this and other cancer types; however, the glycosylation status of MUC1 in cutaneous SCC is not known. Objectives To investigate the expression and glycosylation status of MUC1 in SCCs arising in patients with DEB and JEB, and for comparison in sporadic SCCs and sporadic Bowen's disease. Methods Immunohistochemical analysis of MUC1 in 30 SCCs from subjects with DEB/JEB, 55 sporadic SCCs and 30 sporadic lesions of Bowen's disease was carried out using four separate monoclonal antibodies which recognize different isoforms of MUC1. Results Expression of MUC1 was detected in 100% of SCCs arising in patients with DEB and JEB; > 50% of neoplastic cells stained positive for MUC1 in 57% of DEB/JEB SCCs, with over 95% of tumour cells immunopositive in 33% of cases. MUC1 expression was also observed in 95% of sporadic SCCs and 97% of Bowen's disease, with 36% of sporadic SCCs immunopositive for MUC1 in > 50% of tumour cells. Investigation of the glycosylation status showed that MUC1 was predominantly hyperglycosylated in the DEB/JEB and sporadic tumours. Conclusions The results demonstrate that a significant proportion of DEB/JEB and sporadic SCCs express MUC1 in > 50% of tumour cells. Therefore, MUC1 may be a suitable candidate antigen against which to develop a tumour vaccine for these patient groups.

Altered expression of L-arginine metabolism pathway genes in chronic wounds in recessive dystrophic epidermolysis bullosa.

Abstract: Summary Individuals with the severe, mutilating Hallopeau–Siemens form of recessive dystrophic epidermolysis bullosa (HS-RDEB) have trauma-induced blisters and skin erosions which often progress to wounds that are slow to heal. These chronic wounds cause considerable morbidity and there is an increased risk of squamous cell carcinoma arising in the wound margins. Currently, little is known about the keratinocyte cell biology in these wounds. Therefore, we compared the gene expression profiles of wound edge with nonwounded skin from two individuals with HS-RDEB. Trauma-induced wound sites had been present in both patients for more than 3 months. Hybridizations using DermArrayTM gene expression filters showed relative differences in gene expression between wounded and unwounded skin. Notably, there was a fivefold increase in expression of arginase-1 (ARG1) in the chronic wound samples. Expression of seven other genes relevant to l-arginine metabolism also showed differences greater than twofold. l-Arginine is known to have a critical role in the synthesis of nitric oxide as part of normal tissue repair. Although alterations in arginase isoenzymes have been detected previously in other chronic wounds (human and animal models), this is the first study to demonstrate differences in several components of the l-arginine metabolism pathway in chronic wounds, and the first to examine chronic wounds in HS-RDEB. The data show that the cascade of l-arginine metabolites is altered in HS-RDEB and the findings may provide new insight into the pathology of chronic wounds in this genodermatosis.

Molecular basis of lipoid proteinosis in two Indian siblings.

Abstract: To the Editor: Lipoid proteinosis (OMIM 247100) is a rare autosomal recessive genodermatosis that results from loss-of-function mutations in the extracellular matrix protein 1 (ECM1) gene on chromosome 1q21.2 (1, 2). Over 20 pathogenic mutations have been reported, most of which are specific to individual families (1–4). The ECM1 protein has a wide tissue distribution, including skin, where it has a role in epidermal differentiation, binding of dermal fibrils and angiogenesis (5), all of which may be altered in lipoid proteinosis. Two Indian siblings born to non-consanguineous parents, aged 9 and 12 years, were diagnosed with lipoid proteinosis based on clinical and skin biopsy features that included a hoarse voice from infancy, a short thickened tongue and extensive infiltration and scarring of the skin, as well as deposition of periodic acid Schiff (PAS) -positive material around blood vessels and appendages; these clinico-pathological findings were reported recently in this journal (6). We now follow-up this initial report with molecular analysis. Following informed consent, DNA was extracted from peripheral blood samples taken from the affected siblings and their parents using a standard cold water lysis method. Polymerase chain reaction (PCR) amplification of the ECM1 gene was performed using eight pairs of primers spanning all 10 exons and situated in flanking introns, as described in detail elsewhere (2). All PCR products were then purified using QIA quick PCR Purification Kits (Qiagen, Crawley UK) and sequenced directly in an ABI 310 genetic analyser (Applied Biosystems, Warrington, UK). In addition, we deThe Journal of Dermatology Vol. 31: 764–766, 2004

An Indian child with lipoid proteinosis resulting from a recurrent frameshift mutation (507delT) in the extracellular matrix protein 1 gene.

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