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J Uitto

Publications and source records attributed to J Uitto.

At least 199 records · Page 11Linked to original sources
PubMed1996

Mutational hotspots in the LAMB3 gene in the lethal (Herlitz) type of junctional epidermolysis bullosa.

The Herlitz type of junctional epidermolysis bullosa (H-JEB) is a severe blistering disease affecting the skin and mucous membranes, and laminin 5 has been implicated as the candidate gene/protein system for most patients with H-JEB. In this study, we have examined a cohort of 14 families with H-JEB for mutations in the LAMB3 gene. Premature termination codon mutations were delineated in both alleles of each proband in all pedigrees. Interestingly, two recurrent mutations, R42X and R635X, were noted in over 50% of the mutant LAMB3 alleles. These nonsense mutations occurred at CpG dinucleotide sequences, suggesting hypermutability of 5-methylcytosine to thymine. Additional evidence suggested that R42X and R635X represent mutational hotspots. First, the inheritance of R635X in a homozygous individual on two different genetic backgrounds was demonstrated by haplotype analysis. Furthermore, in one family, R42X was shown to be inherited on the maternal allele which lacked this mutation, suggesting that it arose as a result of maternal germline mutation. Elucidation of these two hotspot mutations will facilitate screening of additional JEB patients for the underlying mutations.

Alleles↗
PubMed1996

Clinicopathological correlations of compound heterozygous COL7A1 mutations in recessive dystrophic epidermolysis bullosa.

Recessive dystrophic epidermolysis bullosa is an inherited mechano-bullous disorder of skin and mucous membranes. Ultrastructurally, the disease is characterized by abnormalities of anchoring fibrils, attachment structures below the epidermal basement membrane, composed of type VII collagen. Mutations in the type VII collagen gene (COL7A1) have been shown conclusively to underlie dystrophic epidermolysis bullosa. Since there is variation of the phenotype, accompanied by heterogeneous anchoring fibril morphology and type VII collagen immunostaining, it is conceivable that different types and combinations of COL7A1 mutations correlate with different phenotypes. We therefore screened recessive dystrophic epidermolysis bullosa patients for COL7A1 mutations. Three unrelated patients showed the same premature termination codon mutation in exon 13 of one allele, yet they were all compound heterozygotes, each having a different mutation in the second allele. The first patient had a premature termination codon within the collagenous region of COL7A1 associated with severe disease, absent anchoring fibrils and undetectable type VII collagen immunostaining. The second had a premature termination codon in the non-collagenous NC-2 region associated with severe disease, wispy anchoring fibrils, and patchy type VII collagen immunostaining. The third had a glycine-to-aspartic acid substitution within the collagenous region, associated with milder disease, no identifiable anchoring fibrils, but near normal type VII collagen immunostaining. We conclude that the nature and position of mutations within COL7A1 correlate with specific disease features and may provide an insight into the molecular mechanisms of anchoring fibril formation and epidermal-dermal adhesion.

Adult↗
PubMed1996

Molecular basis of recessive dystrophic epidermolysis bullosa: genotype/phenotype correlation in a case of moderate clinical severity.

Mutations within the gene encoding the anchoring fibril protein type VII collagen (COL7A1) have recently been established as the pathogenetic basis for the inherited blistering skin disorder, dystrophic epidermolysis bullosa. We report a patient with a moderately severe phenotype of recessive dystrophic epidermolysis bullosa. We report a patient with a moderately severe phenotype of recessive dystrophic epidermolysis bullosa, in whom COL7A1 mutations have been identified on both alleles. The patient is a 5-y-old Japanese male of nonconsanguineous parents, with clinical features including generalized trauma-induced blistering since birth, complete loss of nails, and partial fusion of the fingers and toes. Immunofluorescence microscopy examination of the dermal-epidermal junction in the patient's skin revealed near-normal intensity staining with an antitype VII collagen antibody (LH7:2). Transmission electron microscopy showed a reduced number of thin, poorly-formed anchoring fibrils. PCR amplification of genomic DNA, followed by heteroduplex analysis, and nucleotide sequencing demonstrated that the patient was a compound heterozygote for a nonsense mutation (E2858X) within the NC-2 domain of type VII collagen and a missense mutation (G2576R) within the type VII collagen triple helix. Both mutations were verified by restriction endonuclease digestion. Information about these mutations advances our understanding of genotype-phenotype correlations in dystrophic epidermolysis bullosa, and further delineates the mechanisms involved in dermal-epidermal dysadhesion.

Base Sequence↗
PubMed1996

Compound heterozygosity for nonsense ans missense mutations in the LAMB3 gene in nonlethal junctional epidermolysis bullosa.

Mutations in the genes encoding laminin 5 (LAMA3, LAMB3, and LAMC2) have been delineated in the autosomal recessive blistering skin disorder, junctional epidermolysis bullosa, particularly in the lethal (Herlitz) variant. In this study, we searched for mutations in these genes in two patients with nonlethal forms of junctional epidermolysis bullosa using polymerase chain reaction amplification of genomic DA, followed by heteroduplex analysis and direct automated nucleotide sequencing. Both patients were found to be compound heterozygotes for the same nonsense mutation on one LAMB3 allele, and different missense mutations on the other LAMB3 allele. The combination of a nonsense and a missense mutation in the LAMB3 gene appears to be important in determining the milder clinical phenotype in some cases of the nonlethal forms of junctional epidermolysis bullosa involving abnormalities in laminin 5.

Aged↗
PubMed1996

A common insertion mutation in COL7A1 in two Italian families with recessive dystrophic epidermolysis bullosa.

Recessive dystrophic epidermis bullosa is ultrastructurally characterized by the absence of anchoring fibrils, and genetic analyses have revealed that recessive dystrophic epidermolysis bullosa results from mutations in the type VII collagen gene (COL7A1). The mutations disclosed thus far are largely family specific, with no evidence for mutational hotspot(s). In this study, we report a recurrent premature termination codon mutation detected in two apparently unrelated Italian families in different regions of the country. This mutation, 497insA in exon 4 of COL7A1, was found in combination with two different premature termination codon mutations in these families. Haplotype analysis suggested a shared genetic background in the allele containing the mutation 497insA, suggesting that this genetic lesion may represent an ancestral mutation within the Italian gene pool.

Adult↗
PubMed1996

Influence of the second COL7A1 mutation in determining the phenotypic severity of recessive dystrophic epidermolysis bullosa.

The dystrophic forms of epidermolysis bullosa (DEB) are characterized by fragility of the skin and mucous membranes. The ultrastructural hallmark of DEB is abnormalities in the anchoring fibrils. A recessively inherited variant, the mitis type of DEB (M-RDEB), is characterized by a mild phenotype, including the absence of mutilating scarring of the hands and feet. In this study, we demonstrate that M-RDEB results from the combination of a premature termination codon mutation in one COL7A1 allele, while other mutation consists of different types of genetic lesions. These results define M-RDEB as a distinct clinical entity at the molecular level.

Adult↗
PubMed1996

A homozygous deletion mutation in the gene encoding the 180-kDa bullous pemphigoid antigen (BPAG2) in a family with generalized atrophic benign epidermolysis bullosa.

The 180-kDa bullous pemphigoid antigen (BPAG2) is a candidate gene/protein for mutations in some forms of junctional epidermolysis bullosa. In this study, we searched for mutations in BPAG2 in a large Austrian pedigree with generalized atrophic benign epidermolysis bullosa, a distinct nonlethal form of junctional epidermolysis bullosa, using polymerase chain reaction amplification of genomic DNA, heteroduplex analysis of the polymerase chain reaction products, and direct nucleotide sequencing. We identified a homozygous 2-bp deletion within the coding region of BPAG2 in the affected individuals. This mutation results in a frameshift and downstream stop codons on both alleles, predicting an absence of functional protein. These findings illustrate the molecular basis of the skin fragility in this family and attest to the importance of the 180-kDa bullous pemphigoid antigen in the attachment of the epidermis to the underlying dermoepidermal basement membrane.

Autoantigens↗
PubMed1996

Compound heterozygosity for nonsense and missense mutations in the LAMB3 gene in nonlethal junctional epidermolysis bullosa.

Mutations in the genes encoding laminin 5 (LAMA3, LAMB3, and LAMC2) have been delineated in the autosomal recessive blistering skin disorder, junctional epidermolysis bullosa, particularly in the lethal (Herlitz) variant. In this study, we searched for mutations in these genes in two patients with nonlethal forms of junctional epidermolysis bullosa using polymerase chain reaction amplification of genomic DNA, followed by heteroduplex analysis and direct automated nucleotide sequencing. Both patients were found to be compound heterozygotes for the same nonsense mutation on one LAMB3 allele, and different missense mutations on the other LAMB3 allele. The combination of nonsense and a missense mutation in the LAMB3 gene appears to be important in determining the milder clinical phenotype in some cases of the nonlethal forms of junctional epidermolysis bullosa involving abnormalities in laminin 5.

Aged↗
PubMed1996

Genetic basis of Bart's syndrome: a glycine substitution mutation in type VII collagen gene.

Bart's syndrome was initially described as a genodermatosis characterized by congenital localized absence of the skin, together with blistering and nail abnormalities. Recent analysis of Bart's original kindred demonstrated ultrastructural abnormalities in the anchoring fibrils and linkage of the inheritance of the disease to the region of chromosome 3 near the type VII collagen gene (COL7A1). We have performed mutation analysis in this family by using electrophoretic heteroduplex analysis followed by direct nucleotide sequencing of DNA. These results disclosed a G-to-A transition within exon 73 of COL7A1, which results in a glycine-to-arginine substitution within the triple-helical domain of type VII collagen in affected individuals. In this family, these findings demonstrate that Bart's syndrome is a clinical variant of dominant dystrophic epidermolysis bullosa.

Amino Acid Sequence↗
PubMed1996

A recurrent homozygous nonsense mutation within the LAMA3 gene as a cause of Herlitz junctional epidermolysis bullosa in patients of Pakistani ancestry: evidence for a founder effect.

The anchoring filament protein laminin 5 is abnormally expressed in the skin of patients with Herlitz junctional epidermolysis bullosa (H-JEB). In this study, we performed mutational analysis on genomic DNA from a H-JEB child of first-cousin Pakistani parents, and identified a homozygous C-to-T transition in the LAMA3 gene of laminin 5 resulting in a premature termination codon (CGA-TGA) on both alleles. This mutation, R650X, has been previously reported in two other seemingly unrelated H-JEB individuals of Pakistani ancestry. Although this mutation may represent a mutational hotspot within the LAMA3 gene, haplotype analysis based on a silent intragenic polymorphism (GCC/GCG, alanine 429; GenBank no. L34155), and on three flanking microsatellite polymorphism (D18S45, D18S478, and D18S480), suggests that a common ancestral allele may be present in all three cases.

Base Sequence↗
PubMed1996

Cloning of mouse type VII collagen reveals evolutionary conservation of functional protein domains and genomic organization.

Type VII collagen is the major component of anchoring fibrils, attachment structures necessary for stable association of the dermal-epidermal basement membrane to the underlying dermis. The critical role of the anchoring fibrils in providing integrity to the cutaneous basement membrane zone is attested to by demonstration of mutations in the type VII collagen gene (COL7A1) in patients with dystrophic epidermolysis bullosa. To gain insight into the evolutionary conservation of the type VII collagen gene, in this study we have cloned the entire mouse type VII collagen cDNA and elucidated the intron-exon organization of the corresponding gene, Col7a1. The coding region of the cDNA consists of 8832 nucleotides encoding a polypeptide of 2944 amino acids with a calculated molecular mass of approximately 295 kDa. Computer analysis predicted the presence of an 18-amino acid signal peptide. Comparison of the deduced mouse alpha1(VII) collagen polypeptide with the corresponding human sequence indicated 84.7% identity and 90.4% homology at the amino acid level. In addition, the domain organization, including imperfections and interruptions within the collagenous domain consisting of Gly-X-Y repeat sequences, was highly conserved. The unit of evolutionary period between the full-length human and mouse polypeptides was calculated to be 6.5 million years, however, suggesting relatively rapid evolutionary divergence in comparison to other collagen genes. Elucidation of the intron-exon organization of the mouse Col7a1 gene revealed 118 distinct exons, the same number as present in the human gene. These data indicate a high degree of structural conservation between the human and mouse type VII collagen, supporting the critical role of this collagen as the major component of the anchoring fibrils.

Amino Acid Sequence↗
PubMed1996

Genetic basis of Bart's syndrome: a glycine substitution mutation in the type VII collagen gene.

Bart's syndrome was initially described as a genodermatosis characterized by congenital localized absence of the skin, together with blistering and nail abnormalities. Recent analysis of Bart's original kindred demonstrated ultrastructural abnormalities in the anchoring fibrils and linkage of the inheritance of the disease to the region of chromosome 3 near the type VII collagen gene (COL7A1). We have performed mutation analysis in this family by using electrophoretic heteroduplex analysis followed by direct nucleotide sequencing of DNA. These results disclosed a G-to-A transition within exon 73 of COL7A1, which results in a glycine-to-arginine substitution within the triple-helical domain of type VII collagen in affected individuals. In this family, these findings demonstrate that Bart's syndrome is a clinical variant of dominant dystrophic epidermolysis bullosa.

Amino Acid Sequence↗
PubMed1996

Chronic sun exposure alters both the content and distribution of dermal glycosaminoglycans.

Chronic sun exposure leads to structural and functional alterations in exposed skin. Photoageing is a process distinct from the changes taking place due to chronological ageing. Unique alterations in the dermal extracellular matrix occur as a result of photoageing and are responsible for many of these physiological changes taking place in sun-damaged skin. Accompanying the deposition of abnormal elastic tissue, or solar elastosis, are significant alterations in dermal glycosaminoglycans (GAGs). Accumulation of GAGs as a result of photoageing, as demonstrated in both humans and animal models of photoageing, seems almost paradoxical in view of the large amounts of GAGs present in the skin of newborns, making their skin well hydrated and supple, in sharp contrast to the weathered appearance of photoaged skin. We investigate the relative GAG content of photoaged skin using immunoperoxidase stains specific for hyaluronic acid and chondroitin sulphate, and determine the location of these GAGs using confocal laser scanning microscopy. Our results demonstrate significant increases in GAG staining in sun-damaged vs. sun-protected skin from the same individuals, as measured by computer-based image analysis. Furthermore, confocal laser scanning microscopy reveals that the increased dermal GAGs in sun-damaged skin are deposited on the elastotic material of the superficial dermis of photodamaged skin, and not between collagen and elastic fibres as in normal skin. The abnormal location of GAGs on these fibres may explain the apparent paradoxical weathered appearance of photodamaged skin despite increased GAGs.

Chondroitin Sulfates↗
PubMed1996

First trimester DNA-based exclusion of recessive dystrophic epidermolysis bullosa from chorionic villus sampling.

A 28-year-old woman, who previously had had a child affected with the hereditary blistering skin disorder, recessive dystrophic epidermolysis bullosa, presented at 7 weeks' gestation for prenatal diagnosis. Genomic DNA, obtained from her, her husband (who is a first cousin), their unaffected child, and their previously affected child, was used to screen all 118 exons of the type VII collagen gene (COL7A1) by polymerase chain reaction (PCR) amplification followed by heteroduplex analysis of the PCR products. Established common polymorphisms within the NC-1 region of COL7A1 were informative for both the normal maternal and paternal alleles. In addition, a putative homozygous mutation, a G to C transversion at nucleotide position 7708, was identified in the affected child. This substitution converts a glycine residue (GGT) within the Gly-X-Y region of the type VII collagen triple helix into an arginine residue (CGT), and leads to the creation of a new MnlI restriction site. Both parents and the healthy sibling were shown to be clinically normal heterozygous carriers of this mutation. A chorionic villus biopsy was performed at 10 weeks' gestation and DNA was extracted from the villi. Assessment of informative intragenic markers, and the putative mutation, revealed that the fetus had inherited both the normal maternal and paternal COL7A1 alleles. Thus, first trimester DNA-based prenatal diagnosis predicts that this child is neither affected with recessive dystrophic epidermolysis bullosa, nor is an unaffected carrier of this genodermatosis.

Base Sequence↗
PubMed1996

Molecular complexity of the cutaneous basement membrane zone. Revelations from the paradigms of epidermolysis bullosa.

Spectacular success has recently been made towards elucidation of the molecular basis of various forms of epidermolysis bullosa (EB), a group of heritable blistering skin diseases. The information derived from these studies has already had a profound impact in terms of precise diagnosis and classification, early prenatal prediction of the phenotype and genetic counseling in families at risk for recurrence. This review highlights recent progress made in defining the molecular basis of junctional and dystrophic forms of EB and the genotype/phenotype relationships established from these studies. Extensive molecular studies, such as the ones captured in this review, form a foundation for the rational design of gene therapies to counteract these conditions in the future.

Amino Acid Sequence↗
PubMed1996

Plectin and human genetic disorders of the skin and muscle. The paradigm of epidermolysis bullosa with muscular dystrophy.

Recent progress in understanding the molecular organization of the cutaneous basement membrane zone (BMZ) has revealed an intricate network of structural proteins necessary for stable association of the epidermis to the underlying dermis. Molecular genetics of the cutaneous BMZ has also revealed that defects in as many as nine distinct genes within the dermal-epidermal junction which result in different forms of epidermolysis bullosa (EB), a group of heritable mechano-bullous disorders. We have recently demonstrated that a variant of EB associated with late-onset development of muscular dystrophy (EB-MD, MIM no. 226670) results from mutations in the gene encoding plectin (PLEC1), a cytoskeleton associated attachment protein present in the hemidesmosomal inner plaque and the sarcolemma of the muscle. Consequently, mutations in this multi-functional gene/protein system can result in phenotypic manifestations of EB-MD both in the skin and the muscle. In this overview, we will summarize the domain organization of plectin and the structure of the corresponding gene (PLEC1), as well as the genetic basis of EB-MD in families studied thus far. Elucidation of the molecular basis of this subtype of EB adds to our understanding of the structural and functional complexity of the cutaneous BMZ.

Basement Membrane↗
PubMed1996

8-methoxypsoralen and ultraviolet a radiation activate the human elastin promoter in transgenic mice: in vivo and in vitro evidence for gene induction.

Treatment of skin diseases with the combination of 8-methoxypsoralen and ultraviolet A radiation (PUVA) results in clinical alterations in treated skin that resemble those observed in chronically photodamaged skin. The PUVA-treated patients develop nonmelanoma skin cancers, pigmentary alterations and wrinkling characteristic of sun-induced changes. The major alteration in the dermis of sun-damaged skin is the deposition of abnormal elastic fibers, termed solar elastosis. Up-regulation of elastin promoter activity in dermal fibroblasts explains the excess elastic tissue but not the reason for the aberrant morphology of the elastotic material. In order to study photoaging in an experimental system, we utilized a transgenic mouse line that expresses the human elastin promoter/chloramphenicol acetyltransferase construct in a tissue-specific and developmentally regulated manner. Although UVB radiation has been demonstrated to increase promoter activity in vitro, UVA fails to demonstrate a similar effect at the doses utilized. In this study, we demonstrate the ability of PUVA treatment to up-regulate elastin promoter activity both in vitro and in vivo. These data help to explain the development of photoaging in sun-protected PUVA-treated skin. We attribute the up-regulation of elastin promoter activity in response to PUVA to the formation of DNA photoadducts, which do not occur in response to UVA radiation alone.

Animals↗