A Large Mutational Study in Pachyonychia Congenita

Division of Molecular Medicine, University of Dundee, Dundee, UK.
Journal of Investigative Dermatology (Impact Factor: 6.37). 02/2011; 131(5):1018-24. DOI: 10.1038/jid.2011.20
Source: PubMed

ABSTRACT Pachyonychia congenita (PC) is a rare autosomal dominant skin disorder characterized predominantly by nail dystrophy and painful palmoplantar keratoderma. Additional clinical features include oral leukokeratosis, follicular keratosis, and cysts (steatocysts and pilosebaceous cysts). PC is due to heterozygous mutations in one of four keratin genes, namely, KRT6A, KRT6B, KRT16, or KRT17. Here, we report genetic analysis of 90 new families with PC in which we identified mutations in KRT6A, KRT6B, KRT16, or KRT17, thereby confirming their clinical diagnosis. A total of 21 previously unreported and 22 known mutations were found. Approximately half of the kindreds had mutations in KRT6A (52%), 28% had mutations in KRT16, 17% in KRT17, and 3% of families had mutations in KRT6B. Most of the mutations were heterozygous missense or small in-frame insertion/deletion mutations occurring within one of the helix boundary motif regions of the keratin polypeptide. More unusual mutations included heterozygous splice site mutations, nonsense mutations, and a 1-bp insertion mutation, leading to a frameshift and premature termination codon. This study, together with previously reported mutations, identifies mutation hotspot codons that may be useful in the development of personalized medicine for PC.

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    ABSTRACT: Pachyonychia congenita (PC) is a rare autosomal dominant skin disorder characterized predominantly by hypertrophic nail dystrophy, oral leukokeratosis, and painful palmoplantar keratoderma. It is associated with a mutation in one of five keratin genes, KRT6A, KRT6B, KRT6C, KRT16, or KRT17. The International PC Research Registry (IPCRR) confirms that as of January 2014 there have been 547 cases of PC genetically confirmed. It is estimated that there are between 2000 and 10,000 cases of PC in the world. However, the exact prevalence of PC is not yet established. We report a case of PC-K6a, p.Arg164Pro, in a 40-year-old man. Initially he was diagnosed with onychomycosis and was treated with systemic antifungals. This is the first genetically confirmed case of PC in the Czech Republic.
    Dermatologic Therapy 09/2014; 28(1). DOI:10.1111/dth.12142 · 1.48 Impact Factor
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    ABSTRACT: Background Pachyonychia congenita (PC) is a rare autosomal dominant keratinizing disorder characterized by severe, painful, palmoplantar keratoderma (PPK) and nail dystrophy, often accompanied by oral leukokeratosis, cysts and follicular keratosis. It is caused by mutations in one of five keratin genes; KRT6A, KRT6B, KRT6C, KRT16 or KRT17. Objectives To identify mutations in 84 new families with a clinical diagnosis of PC, recruited by the International Pachyonychia Congenita Research Registry (IPCRR) during the last few years. Methods Genomic DNA isolated from saliva or peripheral blood leukocytes was amplified using primers specific for the PC associated keratin genes and PCR products were directly sequenced. ResultsMutations were identified in 84 families in the PC-associated keratin genes, comprising 46 distinct keratin mutations. Fourteen were previously unreported mutations, bringing the total number of different keratin mutations associated with PC to 105. Conclusions This study has confirmed at the molecular level the clinical diagnosis of PC in these families, by identifying mutations in KRT6A, KRT6B, KRT6C, KRT16 or KRT17.This article is protected by copyright. All rights reserved.
    British Journal of Dermatology 03/2014; 171(2). DOI:10.1111/bjd.12958 · 4.10 Impact Factor
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    ABSTRACT: Pachyonychia congenita (PC), a rare autosomal dominant disorder characterized by hypertrophic nail dystrophy, is classified into two main clinical subtypes: PC-1 and PC-2. PC-1 is associated with mutations in the KRT6A or KRT16 genes, whereas PC-2 is linked to KRT6B or KRT17 mutations. Blood samples were collected from three generations of a new Chinese PC-1 family, including three PC patients and five unaffected family members. A novel missense mutation p.Leu128Pro (c.383T>C) was identified in a highly conserved helix motif in domain 1A of K16. The disease haplotype carried the mutation and cosegregated with the affection status. PolyPhen2 and SIFTS analysis rated the substitution as probably damaging; Swiss-Model analysis indicated that the structure of the mutant protein contained an unnormal α-helix. Overexpression of mutant protein in cultured cells led to abnormal cell morphology. Conclusion: The wider spectrum of KRT16 mutations suggests that changes in codons 125, 127, and 132 are most commonly responsible for PC-1 and that proline substitution mutations at codons 127 or 128 may produce more severe disease. This study extends the KRT16 mutation spectrum and adds new information on the clinical and genetic diversity of PC.
    European Journal of Pediatrics 12/2013; 173(6). DOI:10.1007/s00431-013-2236-8 · 1.98 Impact Factor

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