Genotype-phenotype correlations with TGM1: Clustering of mutations in the bathing suit ichthyosis and self-healing collodion baby variants of lamellar ichthyosis

Department of Dermatology, Our Lady's Children's Hospital, Crumlin, Dublin 12, Ireland.
British Journal of Dermatology (Impact Factor: 4.28). 10/2009; 162(2):448-51. DOI: 10.1111/j.1365-2133.2009.09537.x
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    ABSTRACT: The inversa type of recessive dystrophic epidermolysis bullosa (RDEB-I) is a rare variant of dystrophic epidermolysis bullosa, characterised by blistering in the body flexures, trunk, and mucosa. The cause of this specific distribution is unknown. So far, 20 COL7A1 genotypes have been described in RDEB-I and genotype-phenotype correlations have not been studied extensively. The aim of the study was to gain more insight into the pathophysiology of this intriguing RDEB-I phenotype. Twenty Dutch and British RDEB-I patients, and full genotypes in 18 of them, were identified. The literature on RDEB-I genotypes was reviewed and an extensive genotype-phenotype correlation study for RDEB-I was conducted. All 20 patients had generalised blistering at birth and during early infancy. In most patients, the age of transition from generalised to inversa distribution was before the age of 4 years. A spectrum of disease severity, ranging from the mildest 'mucosal only' phenotype to the severest phenotype with limited acral involvement, was noted. The 29 genotypes of these RDEB-I patients and those reported in the literature revealed that RDEB-I is associated with specific recessive arginine and glycine substitutions in the triple helix domain of type VII collagen. Why these specific arginine and glycine substitutions cause the inversa distribution remains unknown. It was not possible to identify clear differences in location and nature of substituting amino acids between these mutations and missense mutations causing other RDEB phenotypes. It is hypothesised that the higher skin temperature in the affected areas plays an important role in the pathophysiology of RDEB-I.
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    ABSTRACT: The term autosomal recessive congenital ichthyosis (ARCI) refers to a group of rare disorders of keratinization classified as nonsyndromic forms of ichthyosis. This group was traditionally divided into lamellar ichthyosis (LI) and congenital ichthyosiform erythroderma (CIE) but today it also includes harlequin ichthyosis, self-healing collodion baby, acral self-healing collodion baby, and bathing suit ichthyosis. The combined prevalence of LI and CIE has been estimated at 1 case per 138 000 to 300 000 population. In some countries or regions, such as Norway and the coast of Galicia, the prevalence may be higher due to founder effects. ARCI is genetically highly heterogeneous and has been associated with 6 genes to date: TGM1, ALOXE3, ALOX12B, NIPAL4, CYP4F22, and ABCA12. In this article, we review the current knowledge on ARCI, with a focus on clinical, histological, ultrastructural, genetic, molecular, and treatment-related aspects.
    Full-text · Article · Jul 2012 · Actas Dermo-Sifiliográficas
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