Mutations In Ichthyin A New Gene On Chromosome 5Q33 In A New Form Of Autosomal Recessive Congenital Ichthyosis

We report the genomic localization by homozygosity mapping and the identification of a gene for a new form of non-syndromic autosomal recessive congenital ichthyosis. The phenotype usually presents as non-bullous congenital ichthyosiform erythroderma with fine whitish scaling on an erythrodermal background; larger brownish scales are present on the buttocks, neck and legs. A few patients presented a more generalized lamellar ichthyosis. Palmoplantar keratoderma was present in all cases, whereas only 60% of the patients were born as collodion babies. Six homozygous mutations including one nonsense and five missense mutations were identified in a new gene, ichthyin, on chromosome 5q33 in 23 patients from 14 consanguineous families from Algeria, Colombia, Syria and Turkey. Ichthyin encodes a protein with several transmembrane domains which belongs to a new family of proteins of unknown function localized in the plasma membrane (PFAM: DUF803), with homologies to both transporters and G-protein coupled receptors. This family includes NIPA1, in which a mutation was recently described in a dominant form of spastic paraplegia (SPG6). We propose that ichthyin and NIPA1 are membrane receptors for ligands (trioxilins A3 and B3) from the hepoxilin pathway.WoSScopu

Mutations in the gene encoding SLURP-1 in Mal de Meleda

Mal de Meleda (MDM) is a rare autosomal recessive skin disorder, characterized by transgressive palmoplantar keratoderma (PPK), keratotic skin lesions, perioral erythema, brachydactyly and nail abnormalities. We report the refinement of our previously described interval of MDM on chromosome 8qter, and the identification of mutations in affected individuals in the ARS (component B) gene, encoding a protein named SLURP-1, for secreted Ly-6/uPAR related protein 1. This protein is a member of the Ly-6/uPAR superfamily, in which most members have been localized in a cluster on chromosome 8q24.3. The amino acid composition of SLURP-1 is homologous to that of toxins such as frog cytotoxin and snake venom neurotoxins and cardiotoxins. Three different homozygous mutations (a deletion, a nonsense and a splice site mutation) were detected in 19 families of Algerian and Croatian origin, suggesting founder effects. Moreover, one of the common haplotypes presenting the same mutation was shared by families from both populations. Secreted and receptor proteins of the Ly-6/uPAR superfamily have been implicated in transmembrane signal transduction, cell activation and cell adhesion. This is the first instance of a secreted protein being involved in a PPK

Novel mutations in the gene encoding secreted lymphocyte antigen- plasminogen activator receptor-related protein-1 (SLURP-1) and five ancestral haplotypes in patients with Mal de Meleda

Mal de Meleda is a recessive, transgressive palmoplantar keratoderma for which we previously identified mutations in the gene encoding secreted lymphocyte antigen-6/urokinase-type plasminogen activator receptor-related protein-1 (SLURP-1). In this report we describe two new mutations: (i) a founder mutation, which changes a conserved cysteine residue to tyrosine (C99Y) in a large inbred Tunisian pedigree, and (ii) a signal sequence mutation (W15R), which was homozygous in a German family and heterozygous in a Scottish patient. Four ancestral haplotypes were observed in 69 patients from countries around the Mediterranean basin, and an additional haplotype was found in the German and Scottish patients. Key words: palmoplantar keratoderma/Mal de Meleda/ARS (component B) mutations/secreted lymphocyte antigen-6/urokinase-type plasminogen activator receptor related protein-1/ancestral haplotypes/SLURP-1

Genotype-Phenotype Correlations Emerging from the Identification of Missense Mutations in MBTPS2

Item does not contain fulltextMissense mutations affecting membrane-bound transcription factor protease site 2 (MBTPS2) have been associated with Ichthyosis Follicularis with Atrichia and Photophobia (IFAP) syndrome with or without BRESHECK syndrome, with keratosis follicularis spinulosa decalvans, and Olmsted syndrome. This metalloprotease activates, by intramembranous trimming in conjunction with the protease MBTPS1, regulatory factors involved in sterol control of transcription and in cellular stress response. In this study, 11 different MBTPS2 missense mutations detected in patients from 13 unrelated families were correlated with the clinical phenotype, with their effect on cellular growth in media without lipids, and their potential role for sterol control of transcription. Seven variants were novel [c.774C>G (p.I258M); c.758G>C (p.G253A); c.686T>C (p.F229S); c.1427T>C (p.L476S); c.1430A>T (p.D477V); c.1499G>A (p.G500D); c.1538T>C (p.L513P)], four had previously been reported in unrelated sibships [c.261G>A (p.M87I); c.1286G>A (p.R429H); c.1424T>C (p.F475S); c.1523A>G (p.N508S)]. In the enzyme, the mutations cluster in transmembrane domains. Amino-acid exchanges near the active site are more detrimental to functionality of the enzyme and, clinically, associated with more severe phenotypes. In male patients, a genotype-phenotype correlation begins to emerge, linking the site of the mutation in MBTPS2 with the clinical outcome described as IFAP syndrome with or without BRESHECK syndrome, keratosis follicularis spinulosa decalvans, X-linked, Olmsted syndrome, or possibly further X-linked traits with an oculocutaneous component

Syndromes associated with multiple pilomatricomas: When should clinicians be concerned?

BACKGROUND: Multiple pilomatricomas have been linked to various syndromes. However, these associations are poorly defined, leaving practitioners conflicted on management of these patients. OBJECTIVE: To perform a comprehensive review to clarify the strength of these relationships and identify which patients may benefit from additional screening and/or genetic screening. METHODS: A literature search was performed using the PubMed, Ovid, and Cochrane databases. Syndromic, familial, and sporadic cases of multiple pilomatricomas were stratified based on number of pilomatricomas. This information was graphed for visual comparison. RESULTS: Sixty-six syndromic cases from 52 publications were identified, with the majority (54) of cases representing myotonic dystrophy, familial adenomatous polyposis-related syndromes (including Gardner syndrome), Turner syndrome, or Rubinstein-Taybi syndrome. Twenty-five of the 54 cases (46.3%) had six or more pilomatricomas. Of sporadic cases, 128 out of 134 (95.5%) had five or less pilomatricomas. LIMITATIONS: Most articles were case reports and series, which are vulnerable to publication bias. Specific details were not explicitly noted in some original articles, and incomplete data could not always be included in analysis. Syndromes may have been missed in sporadic cases. CONCLUSION: The presence of six or more pilomatricomas is highly suggestive of an underlying syndrome (\u3e95% specificity). These patients should undergo additional screening. Patients with less than six pilomatricomas and family history of myotonic dystrophy, first-degree relative with colon cancer or FAP-related syndrome, or family history of pilomatricomas should also undergo further screening