OBJECTIVE: To explore the genetic basis for a Chinese pedigree affected with pachyonychia congenita (PC). METHODS: With informed consent obtained, peripheral blood samples were taken from the pedigree. Genomic DNA was extracted with a phenol/chloroform method. Based on the clinical manifestation of the patients, candidate genes for PC were selected. Potential mutation was screened by PCR and Sanger sequencing. Suspected mutation was verified in other family members by PCR-high resolution melting (HRM) analysis. Haplotype analysis using microsatellite markers was also carried out to determine the founder of the mutation. RESULTS: A heterozygous c.275A>G (Asn92Ser) mutation was discovered in exon 1 of the KRT17 gene in the proband. PCR-HRM analysis showed that all affected members were heterozygous carriers of the mutation. The same mutation was found in none of the unaffected members. Haplotype analysis and sequencing indicated the mother of the proband to be the founder. CONCLUSION The c.275A>G (Asn92Ser) mutation of the KRT17 gene probably underlies the disease in this pedigree. Above finding has facilitated genetic counseling and prenatal diagnosis for this pedigree.
Asian Continental Ancestry Group ; Humans ; Keratin-17 ; genetics ; Mutation ; Pachyonychia Congenita ; genetics ; Pedigree ; Polymerase Chain Reaction

OBJECTIVETo map and identify the disease gene for the epidermolytic palmoplantar keratoderma (EPPK) in a Uighur family of China.

METHODSBlood samples were collected and genomic DNA was extracted from 48 members of the Xinjiang Uighur family. Six microsatellite repeat sequences on chromosome region 17q12-q21 and 12q13 were selected based on the two known candidate genes KRT9 and KRT1. Two-point linkage analysis and haplotype analysis were performed. Exons and their flanking intronic sequence of the KRT9 gene were amplified by polymerase chain reaction (PCR) and sequenced.

RESULTSData from the marker D17S1787 suggested linkage and yielded a Lod score of 8.65 at theta=0 by using MLINK software. Genotypes and haplotypes were acquired. The disease gene of the EPPK family is located between markers 17/TG/36620115 and D17S846. Chromosome 12q13 region was excluded with the negative Lod score obtained in marker D12S96 (Lod=-infinity at theta=0). No pathogenic mutation was detected in the KRT9 gene.

CONCLUSIONThe disease gene of the EPPK family is located on chromosome region 17q21.2. The keratin 9 gene might not be the disease gene.

China ; Chromosomes, Human, Pair 17 ; genetics ; Female ; Humans ; Keratin-1 ; genetics ; Keratin-9 ; genetics ; Keratoderma, Palmoplantar, Epidermolytic ; ethnology ; genetics ; Male ; Microsatellite Repeats ; Mutation ; Pedigree

OBJECTIVETo investigate the keratin 17 gene (KRT17) mutation in a pedigree with pachyonychia congenita type 2 (PC-II).

METHODSDNA was extracted from the blood samples of the patients, unaffected members of the pedigree, and 100 unrelated healthy controls. PCR was performed to amplify the hot spots in KRT17 gene. PCR products were directly sequenced to detect mutation.

RESULTSA heterozygous 296T-->C mutation was found in all the affected members of this family, which resulted in the substitution of leucine by proline in codon 99 (L99P) in the 1A domain of the KRT17, but not in the healthy individuals from the family and the 100 unrelated controls.

CONCLUSIONThe mutation of KRT17 may play a major role in the pathogenesis of this pedigree with pachyonychia congenita type 2.

Adult ; Asian Continental Ancestry Group ; genetics ; Base Sequence ; China ; ethnology ; Humans ; Keratin-17 ; genetics ; Male ; Molecular Sequence Data ; Mutation ; Pachyonychia Congenita ; ethnology ; genetics ; Sequence Analysis, DNA

BACKGROUND: Psoriasis is a common chronic inflammatory skin disease with 2% to 3% prevalence worldwide and a heavy social-psychological burden for patients and their families. As the exact pathogenesis of psoriasis is still unknown, the current treatment is far from satisfactory. Thus, there is an urgent need to find a more effective therapy for this disease. Keratin 17 (K17), a type I intermediate filament, is overexpressed in the psoriatic epidermis and plays a critical pathogenic role by stimulating T cells in psoriasis. Therefore, we hypothesized that inhibiting K17 may be a potential therapeutic approach for psoriasis. This study aimed to investigate the therapeutic effect of K17-specific small interfering RNA (siRNA) on mice with imiquimod (IMQ)-induced psoriasis-like dermatitis. METHODS: Eight-week-old female BALB/c mice were administered a 5% IMQ cream on both ears to produce psoriatic dermatitis. On day 3, K17 siRNA was mixed with an emulsion matrix and applied topically to the left ears of the mice after IMQ application every day for 7 days. The right ears of the mice were treated in parallel with negative control (NC) siRNA. Inflammation was evaluated by gross ear thickness, histopathology, the infiltration of inflammatory cells (CD3+ T cells and neutrophils) using immunofluorescence, and the expression of cytokine production using real-time quantitative polymerase chain reaction. The obtained data were statistically evaluated by unpaired t-tests and a one-way analysis of variance. RESULTS: The severity of IMQ-induced dermatitis on K17 siRNA-treated mice ears was significantly lower than that on NC siRNA-treated mice ears, as evidenced by the alleviated ear inflammation phenotype, including decreased ear thickness, infiltration of inflammatory cells (CD3+ T cells and neutrophils), and inflammatory cytokine/chemokine expression levels (interleukin 17 [IL-17], IL-22, IL-23, C-X-C motif chemokine ligand 1, and C-C motif chemokine ligand 20) (P < 0.05 vs. the Blank or NC siRNA groups). Compared to the NC siRNA treatment, the K17 siRNA treatment resulted in increased K1 and K10 expression, which are characteristic of keratinocyte differentiation (vs. NC siRNA, K17 siRNA1 group: K1, t = 4.782, P = 0.0050; K10, t = 3.365, P = 0.0120; K17 siRNA2 group: K1, t = 4.104, P = 0.0093; K10, t = 4.168, P = 0.0042; siRNA Mix group: K1, t = 3.065, P = 0.0221; K10, t = 10.83, P < 0.0001), and decreased K16 expression, which is characteristic of keratinocyte proliferation (vs. NC siRNA, K17 siRNA1 group: t = 4.156, P = 0.0043; K17 siRNA2 group: t = 2.834, P = 0.0253; siRNA Mix group: t = 2.734, P = 0.0250). CONCLUSIONS Inhibition of K17 expression by its specific siRNA significantly alleviated inflammation in mice with IMQ-induced psoriasis-like dermatitis. Thus, gene therapy targeting K17 may be a potential treatment approach for psoriasis.
Animals ; Dermatitis ; Disease Models, Animal ; Female ; Humans ; Imiquimod ; Inflammation ; Keratin-17/genetics* ; Mice ; Mice, Inbred BALB C ; Psoriasis/genetics* ; RNA, Small Interfering/genetics* ; Skin