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BACKGROUND: Epidermolysis bullosa simplex (EBS) is an inherited skin disorder caused by mutations in the keratin 5 (KRT5) and keratin 14 (KRT14) genes, with fragility of basal keratinocytes leading to epidermal cytolysis and blistering. OBJECTIVES: In this study, we characterized mutations in KRT5 and KRT14 genes in patients with EBS and investigated their possible structure-function correlations. MATERIALS AND METHODS: Mutations were characterized using polymerase chain reaction (PCR) and DNA sequencing. Further, to explore possible correlations with function, the structural effects of the mutations in segment 2B of KRT5 and KRT14 and associated with EBS in our patients, as well as those reported previously, were modelled by molecular dynamics with the aid of the known crystal structure of the analogous segment of human vimentin. RESULTS: We have identified mutations in the KRT5 and KRT14 genes in 16 of 23 families affected by EBS in the Czech Republic. Eleven different sequence variants were found, of which four have not been reported previously. Novel mutations were found in two patients with the EBS-Dowling-Meara variant (EBS-DM) [KRT14-p.Ser128Pro and KRT14-p.Gln374_Leu387dup(14)] and in three patients with localized EBS (KRT14-p.Leu136Pro and KRT5-p.Val143Ala). Molecular dynamics studies show that the mutations p.Glu411del and p.Ile467Thr perturb the secondary alpha-helical structure of the mutated polypeptide chain, the deletion p.Glu411del in KRT14 has a strong but only local influence on the secondary structure of KRT14, and the structural impact of the mutation p.Ile467Thr in KRT5 is spread along the helix to the C-terminus. In all the other point mutations studied, the direct structural impact was significantly weaker and did not destroy the alpha-helical pattern of the secondary protein structure. The changes of 3-D structure of the KRT5/KRT14 dimer induced by the steric structural impact of the single point mutations, and the resulting altered inter- and intramolecular contacts, are spread along the protein helices to the protein C-terminus, but the overall alpha-helical character of the secondary structure is not destroyed and the atomic displacements induced by mutations cause only limited-scale changes of the quaternary structure of the dimer. CONCLUSIONS: The results of molecular modelling show relationships between patients' phenotypes and the structural effects of individual mutations.

MeSH
dítě MeSH
dospělí MeSH
epidermolysis bullosa simplex genetika patologie MeSH
fenotyp MeSH
fluorescenční mikroskopie MeSH
genetická predispozice k nemoci MeSH
intermediární filamenta ultrastruktura MeSH
keratin-14 genetika MeSH
keratin-5 genetika MeSH
kůže ultrastruktura MeSH
lidé MeSH
molekulární modely MeSH
mutace MeSH
předškolní dítě MeSH
Check Tag
dítě MeSH
dospělí MeSH
lidé MeSH
mužské pohlaví MeSH
předškolní dítě MeSH
ženské pohlaví MeSH
Publikační typ
časopisecké články MeSH
práce podpořená grantem MeSH

Článek

Substituce v promotoru CYP21 genu ovlivňují fenotyp nemoci u pacientů s deficitem 21-hydroxylázy
[Substitution in the promoter region of the CYP21 affects a phenotype of the disease in patients with 21-hydroxylase deficiency]

Vrzalová, Zuzana
Autor Autorita
Sťahlová-Hrabincová, Eva
Autor Autorita
Jeřábková, Barbora
Autor Autorita
Votava, Felix, 1957-
Autor Autorita
Kozák, Libor, 1960-2007
Autor Autorita
Fajkusová, Lenka, 1963-
Autor Autorita

Kazuistiky v diabetologii. 2009 ; 7 (1) : 30-33 příl.. (Endokrinologie)

ISSN 1214-231X
Medvik
Zdroj

Souhrn: V kazuistice je prezentován případ šestiletého chlapce, u kterého byla pozorována manifestace předčasné puberty a nadměrný vzrůst postavy. Jeho klinické příznaky odpovídaly prosté virilizující formě kongenitální adrenální hyperplázie. Pro potvrzení stanovené diagnózy byl proband poslán na molekulárně genetické vyšetření deficitu 21-hydroxylázy. Provedením základní DNA analýzy jsme probanda určili jako složeného heterozygota přenášejícího chimérní CYP21P/CYP21 gen na paternální alele a neznámou mutaci na maternální alele. Pomocí metody MLPA a následné sekvenační analýzy CYP21 genu jsme na maternální alele charakterizovali atypickou mutantní alelu s rozsáhlou genovou konverzí (5'– nepřekládaná oblast včetně promotoru a sekvence 1. exonu v CYP21 genu). Bylo popsáno, že tento typ alely významně snižuje aktivitu enzymu 21-hydroxylázy (na 4–10 %), což má za následek projev těžší formy onemocnění CAH, nejčastěji prosté virilizující.

In family report there is presented the case of the six-year-old boy, who was being observed for the manifestation of praecox pubarche and for excessive growth of the figure. His clinical symptomts corresponded to the simple virilizing form of congenital adrenal hyperplasia. To confirm the given diagnose the patient was examined by the molecular genetic analysis of deficit 21-hydroxylase. After the basic DNA analysis the genotype of the boy was determined as the compound heterozygote carrying the chimeric CYP21P/CYP21 gene on the paternal allele and an unknown mutation on the maternal allele. Using the MLPA method and sequencing method of the CYP21 gene we defined atypical mutant allele with a large gene conversion on maternal allele (5'– untranslated region including the promotor and sequence of the 1. exon in the CYP21 gene). It was described that this type of allele significantly decreases the activity of the enzyme 21-hydroxylase enzyme (to 4–10 %), which results in the manifestation of more difficult form of CAH disease, mostly SV form.