Kindler syndrome is an autosomal recessive disorder characterized by neonatal blistering, sun sensitivity, atrophy, abnormal pigmentation, and fragility of the skin. Linkage and homozygosity analysis in an isolated Panamanian cohort and in additional inbred families mapped the gene to 20p12.3. Loss-of-function mutations were identified in the FLJ20116 gene (renamed "KIND1" [encoding kindlin-1]). Kindlin-1 is a human homolog of the Caenorhabditis elegans protein UNC-112, a membrane-associated structural/signaling protein that has been implicated in linking the actin cytoskeleton to the extracellular matrix (ECM). Thus, Kindler syndrome is, to our knowledge, the first skin fragility disorder caused by a defect in actin-ECM linkage, rather than keratin-ECM linkage.

Lipoid proteinosis (LP), also known as hyalinosis cutis et mucosae or Urbach-Wiethe disease (OMIM 247100) is a rare, autosomal recessive disorder typified by generalized thickening of skin, mucosae and certain viscera. Classical features include beaded eyelid papules and laryngeal infiltration leading to hoarseness. Histologically, there is widespread deposition of hyaline (glycoprotein) material and disruption/reduplication of basement membrane. The aetiology of LP is currently unknown. Using DNA from three affected siblings in a consanguineous Saudi Arabian family we performed genome-wide linkage and mapped the disorder to 1q21 (marker D1S498) with a two-point LOD score of 3.45 at theta = 0. A further 28 affected individuals from five other unrelated consanguineous family groups from different geographical regions also showed complete linkage and resulted in a maximum two-point LOD score of 21.85 at theta = 0. Using available markers in the interval between D1S442 and D1S305, the observed recombinants placed the gene in a 2.3 cM critical interval between D1S2344 and D1S2343 (Marshfield genetic map) corresponding to an approximately 6.5 Mb region on the UCSC physical map. Using a candidate gene approach (comparison of control versus LP gene expression in cultured fibroblasts) and subsequent direct sequencing of genomic DNA, we identified six different homozygous loss-of-function mutations in the extracellular matrix protein 1 gene (ECM1). Although the precise function of ECM1 is not known, our findings provide the first clinical indication of its relevance to skin adhesion, epidermal differentiation, wound healing, scarring, angiogenesis/angiopathy and basement membrane physiology, as well as defining the molecular basis of this inherited disorder.

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The autosomal recessive disorder lipoid proteinosis results from mutations in extracellular matrix protein 1 (ECM1), a glycoprotein expressed in several tissues (including skin) and composed of two alternatively spliced isoforms, ECM1a and ECM1b, the latter lacking exon 7 of this 10-exon gene (ECM1). To date, mutations that either affect ECM1a alone or perturb both ECM1 transcripts have been demonstrated in six cases. However, lipoid proteinosis is clinically heterogeneous with affected individuals displaying differing degrees of skin scarring and infiltration, variable signs of hoarseness and respiratory distress, and in some cases neurological abnormalities such as temporal lobe epilepsy. In this study, we sequenced ECM1 in 10 further unrelated patients with lipoid proteinosis to extend genotype-phenotype correlation and to add to the mutation database. We identified seven new homozygous nonsense or frameshift mutations: R53X (exon 3); 243delG (exon 4); 507delT (exon 6); 735delTG (exon 7); 785delA (exon 7); 892delC (exon 7) and 1190insC (exon 8), as well as two new compound heterozygous mutations: W160X/F167I (exon 6) and 542insAA/R243X (exons 6/7), none of which were found in controls. The mutation 507delT occurred in two unrelated subjects on different ECM1 haplotypes and may therefore represent a recurrent mutation in lipoid proteinosis. Taken with the previously documented mutations in ECM1, this study supports the view that exons 6 and 7 are the most common sites for ECM1 mutations in lipoid proteinosis. Clinically, it appears that mutations outside exon 7 are usually associated with a slightly more severe mucocutaneous lipoid proteinosis phenotype, but neurological features do not show any specific genotype-phenotype correlation.

Lipoid proteinosis is a rare, autosomal recessive disorder that presents in early infancy with hoarseness, followed by pox-like and acneiform scars, along with infiltration and thickening of the skin and certain mucous membranes. Histological and ultrastructural examination reveals widespread deposition of hyaline-like material and disruption/reduplication of basement membrane around blood vessels and at the dermal--epidermal junction. Recently, lipoid proteinosis was mapped to 1q21 and pathogenetic loss-of-function mutations were identified in the extracellular matrix protein 1 gene (ECM1). This article reviews the molecular basis of lipoid proteinosis and reassesses the clinico-pathological features of this disorder in light of the new genetic discoveries.

Lipoid proteinosis (OMIM 247100), also known as Urbach-Wiethe disease or hyalinosis cutis et mucosae, is a rare autosomal recessive disorder characterized by generalized thickening and scarring of the skin and mucosae. In 2002, the disorder was mapped to a locus on chromosome 1q21 and pathogenic mutations were identified in the ECM1 gene, which encodes for the glycoprotein extracellular matrix protein 1 (ECM1). ECM1 has since been shown to have several important biological functions. It has a role in the structural organization of the dermis (binding to perlecan, matrix metalloproteinase-9 and fibulin) as well as being targeted as an autoantigen in the acquired disease lichen sclerosus. ECM1 also shows over-expression in certain malignancies and is abnormally expressed in chronologically aged and photo-aged skin. Thus far, 26 different inherited mutations in ECM1 have been reported in lipoid proteinosis. In this article, we provide an update on the molecular pathology of lipoid proteinosis, including the addition of 15 new mutations in ECM1 to the mutation database, and review the biological functions of the ECM1 protein in health and disease.

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Pemphigus is a life-threatening autoimmune blistering disease. Pemphigus is divided into 4 major types; pemphigus vulgaris, pemphigus foliaceus, paraneoplastic pemphigus, and IgA pemphigus. Among them, IgA pemphigus is characterized by tissue-bound and circulating IgA antibodies targeting desmosomal or nondesmosomal cell surface components in the epidermis. Histopathologically, slight epidermal acantholysis and extensive neutrophilic infiltration in either the upper part or all layers of the epidermis were observed. IgA pemphigus is subdivided into intraepidermal neutrophilic IgA dermatosis-type (IEN-type), whose target antigen is still unknown (probably nondesmosomal cell surface protein), and subcorneal pustular dermatosis-type (SPD-type), whose target antigen is desmocollin 1 (Dsc1). We summarize reported cases of IgA pemphigus and describe current knowledge including epidemiology, clinical manifestations, pathology, laboratory tests, pathophysiology, associated diseases, prognosis and treatment, and future perspectives of IgA pemphigus.