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At least 19 recordsLinked to original sources

PubMed2001

Novel mutations of the transglutaminase 1 gene in lamellar ichthyosis.

Lamellar ichthyosis, one form of congenital autosomal recessive ichthyosis, is caused by mutations in the gene (TGM1) encoding the transglutaminase 1 enzyme. Mutations, deletions, or insertion of TGM1 have been reported so far. Here we report that three novel mutations of TGM1, D101V, N288T, and R306W, cause lamellar ichthyosis in two different families. The patient in family LI-KD has N288T and R306W mutations, and the patient in family LI-LK has D101V and R306W mutations. The activity of the transglutaminase 1 enzyme of the patient in family LI-LK was only about 15% of normal. Also, three-dimensional structural prediction analyses revealed that the N288T and R306W mutations, and possibly the D101V mutation, cause misfolding in the central catalytic core domain of the transglutaminase 1 enzyme that would probably result in reduced enzyme activity. Our data suggest that the greatly reduced transglutaminase 1 activities are due to disruptions of the native folding of transglutaminase 1, and that these mutations may play a critical role in the pathology of lamellar ichthyosis.

Amino Acid Substitution↗

PubMed1995

Mutations of keratinocyte transglutaminase in lamellar ichthyosis.

Lamellar ichthyosis is a severe congenital skin disorder characterized by generalized large scales and variable redness. Affected individuals in three families exhibited drastically reduced keratinocyte transglutaminase (TGK) activity. In two of these families, expression of TGK transcripts was diminished or abnormal and no TGK protein was detected. Homozygous or compound heterozygous mutations of the TGK gene were identified in all families. These data suggest that defects in TGK cause lamellar ichthyosis and that intact cross-linkage of cornified cell envelopes is required for epidermal tissue homeostasis.

Base Sequence↗

PubMed1999

Identification of mutations in the transglutaminase 1 gene in lamellar ichthyosis.

Lamellar ichthyosis (LI) is an autosomal recessive disorder of cornification. Mutations in the transglutaminase 1 gene (TGM1) have been identified in several families with this disorder. We analyzed two unrelated families with offspring affected with LI. Family 1 included affected monozygotic twins, in which a homozygous G-to-T transversion was identified in exon 6 at amino acid residue R315L. This mutation was also identified in the unaffected mother. In family 2, which consisted of one affected infant, a T-to-G transversion in exon 8 resulted in a change of phenylalanine to valine, F400V, and a C-to-T transition in exon 4 resulted in a change of proline to leucine, P248L. In this family, the mutation F400V was found in the unaffected father, and the mutation P248L was identified in the unaffected mother. These findings extend the growing body of literature documenting mutations in the TGM1 gene as the molecular basis of certain cases of lamellar ichthyosis.

Amino Acid Sequence↗

PubMed2000

Haplotype association and mutation analysis of the transglutaminase 1 gene for prenatal exclusion of lamellar ichthyosis.

Lamellar ichthyosis (LI) is an autosomal recessive keratinization disorder of the skin. Genetic heterogeneity has been shown for the disease and there is evidence for the involvement of the transglutaminase 1 (TGM1) gene on chromosome 14q11. We have previously identified chromosome 14q11 haplotypes associated with ichthyosis in the Norwegian population. In this paper we describe antenatal exclusion of ichthyosis in two Norwegian families by chromosome 14q11 haplotype association and direct mutation analysis. In one pregnancy, the 11-week old fetus at risk for LI was found to share only one disease-associated haplotype. A subsequent mutation analysis of the TGM1 gene in fetal DNA revealed that the fetus carried a novel 3795A-->T transversion. The affected proband was compound heterozygous for the mutations 3795A-->T and 3239G-->C resulting in an Asp430Val and a Val379Leu, respectively. In another LI family, the 11-week old fetus was found to be heterozygous for the 14q11 haplotype associated with the disease. Subsequent mutation analysis revealed that the fetus was heterozygous for the 2526A-->G transition in the splice site of intron 5 whereas the proband was homozygous for the same mutation. Our results show that haplotyping can be a useful tool for prenatal diagnosis in diseases with genetic heterogeneity.

Chromosomes, Human, Pair 14↗

PubMed1996

Corrective gene transfer in the human skin disorder lamellar ichthyosis.

Lamellar ichthyosis (LI) is a disfiguring skin disease characterized by abnormal epidermal differentiation and defective cutaneous barrier function. LI has been associated with loss of keratinocyte transglutaminase 1 (TGase1), an enzyme believed necessary for normal formation of the cornified epidermal barrier. Using LI as a prototype for therapeutic cutaneous gene delivery, we have used the human skin/immunodeficient mouse xenograft model to correct the molecular, histologic and functional abnormalities of LI patient skin in vivo. We have used TGase1-deficient primary keratinocytes from LI patients combined with high-efficiency transfer of functional TGase1 to regenerate engineered human LI epidermis on immunodeficient mice. Engineered LI epidermis displayed normal TGase1 expression in vivo, unlike unengineered LI epidermis where TGase1 was absent. Epidermal architecture was also normalized by TGase1 restoration, as was expression of the epidermal differentiation marker filaggrin. Engineered LI skin demonstrated restoration of cutaneous barrier function measures to levels seen in epidermis regenerated by keratinocytes from patients with normal skin, indicating functional correction in vivo of the proposed primary pathophysiologic defect in LI. These results confirm a major role for TGase1 in epidermal differentiation and demonstrate a potential future approach to therapeutic gene delivery in human skin.

3T3 Cells↗

PubMed1998

Differential patterns of filaggrin expression in lamellar ichthyosis.

Lamellar ichthyosis (LI) is a rare genetic and congenital disturbance of keratinization that is phenotypically and genotypically heterogeneous. Filaggrin is one of the major components of the stratum corneum situated in the protein matrix and the cornified envelope. In view of the heterogeneity of LI, this study aimed at exploring filaggrin expression in the skin of patients suffering from the disease. Epidermal filaggrin expression was determined using immunohistochemical techniques and Western blot in 12 patients with LI and the findings were compared with those observed in four normal controls and eight patients with ichthyosis vulgaris. With Western blot, six different patterns of filaggrin expression were detected. The patients with similar clinical manifestations showed a similar pattern, as did members of the same family. Overall, higher filaggrin expression in scales correlated with a better prognosis. In patients receiving retinoids no variations in filaggrin expression during treatment were detected. Our results suggest that LI is heterogeneous as regards filaggrin expression. Filaggrin could therefore be used as a prognostic marker as well as being a marker of the basic defect involved in LI.

Blotting, Western↗

PubMed1977

The keratinization disorder in collodion babies evolving into lamellar ichthyosis. Its possible relevance for determining the primary defect in lamellar ichthyosis.

Two collodion baby girls with disorder evolving into lamellar ichthyosis were followed by light and electron microscopy. Light microscopically, the neonatal colloidion skin was characterized by a thick compact stratum corneum which was PAS positive in its upper two thirds, by a thin stratum granulosum and by a non-acanthotic stratum spinosum with normal mitotic activity. Electron microscopically, the upper stratum corneum appeared pathological, whereas the lower part was normal except for some minor parakeratosis. The main alterations in the underlying stratum granulosum were diminished tonofibrils and keratohyalin. Biopsy specimens taken at the age of 2 weeks were typical for lamellar ichthyosis and showed hyperkeratosis with focal parakeratosis, a thickened stratum granulosum in which the cellular content of keratohyalin and tonofibrils was moderately diminished, and acanthosis with increased mitotic activity. It appears that the ultrastructural changes of the stratum granulosum, seen in lamellar ichthyosis, are already present in the collodion skin of the newborn, at a time when the epidermis does not yet show an increase in mitotic activity.

Female↗

PubMed1999

Surgical treatment of cicatricial ectropion in lamellar ichthyosis.

BACKGROUND. Lamellar ichthyosis is a skin disorder that is frequently associated with cicatricial ectropion and lagophthalmos. The authors present the surgical management of cicatricial ectropion in a case with lamellar ichthyosis. PATIENT AND METHODS. A 2-year-old male presented with bilateral cicatricial ectropion of the upper and lower eyelids. He had lagophthalmos and corneal punctuate staining. His skin was totally involved with the disease process except his prepuce. The patient was circumcised, and after the correction of horizontal eyelid laxity, the penile skin graft was sutured into the defects in all four eyelids. RESULTS. 18 months following surgery the patient had no lagophthalmos or corneal exposure, but had slight ectropion at the temporal side of the left lower eyelid. He had no complications from the circumcision. CONCLUSION. Prepuce is an alternative donor tissue in male patients with no other available donor site. To our knowledge, this is the second report of cicatricial ectropion corrected with a penile skin graft.

Journal Article↗

PubMed1998

Genotype/phenotype correlation in autosomal recessive lamellar ichthyosis.

Autosomal recessive lamellar ichthyosis is a severe congenital disorder of keratinization, characterized by variable erythema of the whole body surface and by different scaling patterns. Recently, mutations have been identified in patients with lamellar ichthyosis in the TGM1 gene coding for keratinocyte transglutaminase, and a second locus has been mapped to chromosome 2. We have now analyzed the genotype/phenotype correlation in a total of 14 families with lamellar ichthyosis. Linkage analyses using microsatellites in the region of the TGM1 gene confirmed genetic heterogeneity. In patients not linked to the TGM1 gene, the second region identified on chromosome 2 and a further candidate region on chromosome 20 were excluded, confirming as well the existence of at least three loci for lamellar ichthyosis. Sequence analyses of the TGM1 gene in families compatible with linkage to this locus revealed seven different missense mutations, five of these unpublished so far, and one splice mutation. No genotype/phenotype correlation for mutations in the TGM1 gene was found in this group of patients, which included two unrelated patients homozygous for the same mutation. Similarly, no clear difference in the clinical picture was seen between patients with TGM1 mutations and those unlinked to the TGM1 locus. Comparison of genetic and clinical classifications for patients with lamellar ichthyosis shows no consistency and thus indicates that clinical criteria currently in use cannot discriminate between the molecularly different forms of the disease.

Genes, Recessive↗

PubMed1998

Genetic and immunohistochemical detection of mutations inactivating the keratinocyte transglutaminase in patients with lamellar ichthyosis.

Autosomal recessive lamellar ichthyosis is a clinically heterogeneous group of severe congenital keratinization disorders that is characterized by generalized hyperkeratosis and variable erythema. About half of the patients have mutations in the TGM1 gene, which encodes the keratinocyte transglutaminase. Linkage studies have shown that at least two further loci for autosomal recessive lamellar ichthyosis must exist. We present here two patients with lamellar ichthyosis caused by mutations in the TGM1 gene. The first patient is compound heterozygous for the novel missense mutation C53S and the splice mutation A3447G. The second patient, a child of consanguineous parents from Tunisia, is homozygous for the unknown nonsense mutation W263X. This is the first report of a mutation, C53S, that affects the region of the keratinocyte transglutaminase that is essential for anchorage of the enzyme to the plasma membrane. A novel, rapid in situ transglutaminase activity assay revealed the absence of keratinocyte transglutaminase activity in both patients. The mutations described are hence causative for the ichthyosis phenotype.

Adolescent↗

PubMedDate not supplied

Bathing-suit ichthyosis. A peculiar phenotype of lamellar ichthyosis in South African blacks.

Autosomal recessive congenital ichthyosis is a heterogeneous group of disorders of cornification showing a wide spectrum of clinical phenotypes.Here, thirteen cases of a so far unreported distinct type of autosomal recessive congenital ichthyosis are described. All the skin lesions were present at birth and ten were then compatible with collodion baby. Shedding of the collodion led to an ichthyotic condition with a very characteristic distribution of the lesions which involved the trunk, the most proximal parts of the upper limbs, scalp and neck but spared the central face and extremities. The term "bathing-suit" ichthyosis is suggested for this unusual phenotype of lamellar ichthyosis.

Adolescent↗

PubMedDate not supplied

Altered expression of immunoreactive involucrin in lamellar ichthyosis.

In some cases of lamellar ichthyosis, mutations in the epidermal transglutaminase gene and a reduction in the thickness of the cornified envelope have been documented. Involucrin is a major component of the cornified envelope and a substrate for epidermal transglutaminase. The aim of the present work was to analyse the expression of involucrin in lamellar ichthyosis. An ultrastructural study and/or immunohistochemical and biochemical techniques with anti-involucrin antibody were carried out on the epidermis of fifteen patients (12 families) suffering from lamellar ichthyosis. The effect of in vivo retinoid treatment on the involucrin epidermal expression was also investigated. Four cases with normal skin, seventeen cases of other ichthyoses and ten cases of psoriasis were used as controls. In all these cases of lamellar ichthyosis, a thin or absent cornified envelope, electron-dense granules inside corneocytes and a decrease of the epidermal involucrin expression were observed. In the patients receiving treatment with retinoids, western blot and ELISA revealed an increase in the involucrin expression. The decreased expression of involucrin in lamellar ichthyosis could contribute to the altered desquamation process accompanying the disease, since the clinical improvement associated with retinoid treatment is accompanied by an increase in the expression of involucrin.

Blotting, Western↗

PubMed2003

Mutations in the transporter ABCA12 are associated with lamellar ichthyosis type 2.

Lamellar ichthyosis type 2 (LI2) is a rare autosomal recessive skin disorder for which a gene has been localized on chromosome 2q33-35. We report the identification of five missense mutations in the ABCA12 gene in nine families from Africa affected by LI2. The mutations were homozygous in eight consanguineous families and heterozygous in one non-consanguineous family. Four of these mutations are localized in the first ATP-binding domain (nucleotide-binding fold), which is highly conserved in all ABC proteins. The ABCA12 protein belongs to a superfamily of membrane proteins that translocate a variety of substrates across extra- and intracellular membranes. ABCA transporters have been implicated in several autosomal recessive disorders, notably of lipid metabolism. By analogy with ABCA3, a lamellar body membrane protein in lung alveolar type II cells, ABCA12 could function in cellular lipid trafficking in keratinocytes.

Black People↗

PubMed1984

Autosomal dominant lamellar ichthyosis: a new skin disorder.

Lamellar ichthyosis (nonbullous congenital ichthyosis) has been explained as an autosomal recessive trait. We have found an autosomal dominant type of this disorder. Four patients, belonging to three consecutive generations of a family, were affected from birth. The disorder was characterized by large, dark brown scales covering the entire body including flexural folds, palms and soles. X-linked recessive ichthyosis was excluded by clinical appearance, pattern of transmission and normal electrophoretic mobility of beta-lipoproteins. Autosomal dominant ichthyosis vulgaris and bullous ichthyosiform erythroderma were excluded by the histological and ultrastructural features. In the absence of a positive family history, this skin disorder would have been taken for autosomal recessive lamellar ichthyosis. This new autosomal dominant type of ichthyosis should be considered for differential diagnosis, when genetic counselling is given in a sporadic case of lamellar ichthyosis.

Child↗

PubMed1985

Autosomal-dominant lamellar ichthyosis: ultrastructural characteristics of a new type of congenital ichthyosis.

Recently, autosomal-dominant lamellar ichthyosis (ADLI) has been shown to be a new genetic trait with clinical and histologic features similar to those of autosomal-recessive lamellar ichthyosis. In two patients affected with ADLI, the malpighian keratinocytes showed ultrastructural signs of increased cellular metabolism. The tonofilaments and keratohyaline granules were regular in structure and number. However, as a distinctive ultrastructural feature, a prominent transforming zone was found between the granular and horny layers. Moreover, a normal keratin pattern and only a limited number of lipid inclusions were observed in the stratum corneum. Thus, ADLI can be distinguished from the autosomal-recessive forms of lamellar ichthyosis, permitting a correct diagnosis when genetic counselling has to be given in sporadic cases.

Adult↗

PubMed1985

Heterogeneity in autosomal recessive ichthyosis. Clinical and biochemical differentiation of lamellar ichthyosis and nonbullous congenital ichthyosiform erythroderma.

Nonbullous congenital ichthyosiform erythroderma (CIE) and classic lamellar ichthyosis (LI) can be distinguished by clinical, histopathologic, and biochemical findings reported herein. Whereas all patients with CIE (n = 12) had fine white scales, they were heterogeneous with respect to degree of erythroderma, ectropion, and prognosis. In contrast, all patients with LI (n = 6) had large, dark, platelike scales, severe ectropion that showed no improvement with age, and minimal erythroderma. Although the stratum corneum of patients with LI was two to three times thicker than that of those with CIE, the latter group demonstrated more acanthosis, parakeratosis, hypergranulosis, and less prominent dermal capillaries. Studies of scale-lipid content have indicated biochemical correlates of this clinical heterogeneity. These clinical, histologic, and biochemical findings provide useful guidelines to differentiate CIE from LI and strongly suggest that autosomal recessive primary ichthyosis comprises two distinct diseases.

Adolescent↗

PubMed1989

Cyclosporine in lamellar ichthyosis.

In an open trial, five patients with lamellar ichthyosis showed no response to four weeks of treatment with oral cyclosporine (cyclosporine A) (6 mg/kg/d). Histologic examination of lamellar ichthyosis revealed hyperkeratosis; psoriasiform acanthosis; dilated, tortuous capillaries; and a slight perivascular lymphocytic infiltrate. Immunofluorescence studies revealed, in the epidermis, normal numbers of T6+DR+ Langerhans' cells and an absence of T cells and intercellular adhesion molecule-1 expression. In the papillary dermis, there were prominent capillaries as detected by staining with anti-factor VIII-related antigen. The endothelial cells also expressed large amounts of HLA-DR and intercellular adhesion molecule-1, suggesting that they were activated. Only occasional Langerhans' cells were found in the dermis. Histologic and immunofluorescence findings were unchanged with cyclosporine therapy. The effects of cyclosporine on lamellar ichthyosis are contrasted with those reported for psoriasis. Since lamellar ichthyosis and psoriasis share similar features of epidermal hyperproliferation and the presence of activated, dilated, tortuous vessels, but differ in the lack of immunologic cellular activity, their contrasting response to cyclosporine suggests that the target of the action of cyclosporine is the immune system rather than the keratinocyte or the endothelium. However, other factors may have to be considered.

Adult↗

PubMed1996

Mapping of a second locus for lamellar ichthyosis to chromosome 2q33-35.

Lamellar ichthyosis (LI) is an inherited autosomal recessive disorder of cornification. It was recently demonstrated to result from deleterious mutations in the transglutaminase 1 (TGM1) gene. However, the disease was shown to be genetically heterogeneous, since some families were found to be unlinked to TGM1. Homozygosity mapping on three consanguinous families originating from Morocco shows (i) absence of linkage with TGM1 and other regions of the genome containing genes involved in cornification, and (ii) location of a second disease-causing gene on chromosome 2q33-35. A maximum two-point lodscore of 7.60 was obtained with D2S157 for theta = 0. The analysis of recombination events places the gene within a 7-8 cM interval. Additional consanguinous pedigrees were also demonstrated to be unlinked both to TGM1 and to 2q33-35, suggesting the existence of at least a third disease-causing gene.

Chromosome Mapping↗