Identification of a novel mutation and a genetic polymorphism of EVER1 gene in two families with epidermodysplasia verruciformis

BACKGROUND: Epidermodysplasia verruciformis (EV) is a rare autosomal recessive disease. The main clinical features include three kinds of lesions, high risk of skin cancer, and abnormal susceptibility to HPV 5 and 8. Recent studies have shown that mutations in EVER1 and EVER2 genes are responsible for the condition. OBJECTIVE: In the present study, we investigated the molecular basis of EV in two families with EV. METHODS: PCR and direct sequencing of the EVER1 and EVER2 genes were used to identify and confirm the mutations in our probands in the two families. Direct sequencing and SacI digestion were used to detect the polymorphism of exon 6. RESULTS: Sequencing of the EVER1 and EVER2 genes revealed a novel mutation and a genetic polymorphism. The novel mutation by inserting CATGT after nucleotide 916 in exon 9 resulted in a nonsense mutation and a premature termination codon. Direct sequencing and SacI digestion revealed genotype frequencies of C457T, 457T, and 457C alleles in 16 individuals of EV families were of 9, 3, and 4, which were 26, 0, and 24 in 50 unrelated normal controls, respectively. To our knowledge, the novel mutation and genetic polymorphism have not been described in literatures. CONCLUSIONS: The growing number of mutations in EV pedigrees supports the hypothesis that EVER1 and EVER2 are the molecular basis of EV.     

Treatment of a patient with epidermodysplasia verruciformis carrying a novel EVER2 mutation with imiquimod

Epidermodysplasia verruciformis (EV) is a rare disorder characterized by widespread human papillomavirus infection and malignant transformation. EV may be caused by mutations of the genes EVER1 or EVER2, which are located on the EV1 locus, 17q25. We describe a patient with EV and a novel homozygous gene mutation of EVER2 gene who was treated successfully with topical imiquimod.     

Novel homozygous frameshift mutation of EVER1 gene in an epidermodysplasia verruciformis patient

Epidermodysplasia verruciformis (EV) is a rare genetic skin disease with an autosomal recessive trait, and the patients have susceptibility to a specific group of human papillomavirus genotypes. Recently germline mutations in EVER1/2 genes have been detected in EV patients with different ethnic origins. In this study, we have applied PCR, single-stranded conformational polymorphism analysis, and sequencing as well as restriction fragment length polymorphism analysis for identifying potential mutation(s) of EVER genes in an EV patient and in the parents of Pakistani origin. A novel homozygous frameshift mutation (T base deletion at nucleotide position 968 of DNA) has been detected in the EVER1 gene of the patient. The parents carried this mutated allele in a heterozygous form. This is the third report on the presence of EVER1 mutations in an EV patient, and this result supports better understanding, diagnosis, and genetic counseling of EV patients.     

Epidermodysplasia Verruciformis in Lipoid Proteinosis: Case Report and Discussion of Pathophysiology

Lipoid proteinosis (LP) is a rare autosomal recessive genodermatosis caused by mutations in extracellular matrix protein 1 (ECM1) that involves deposition of basement membrane–like material in the skin and other organs. Epidermodysplasia verruciformis (EV) is also a rare autosomal recessive genodermatosis involving susceptibility to human papillomavirus (HPV) infections and squamous cell carcinoma, caused in most cases by homozygous mutations in EVER1 or EVER2. We describe a case of EV in a patient with LP and discuss the pathophysiology. A 3‐year‐old Lebanese girl presented with hoarseness, beaded papules along the eyelid margins, waxy papules and plaques on her head and neck, and lichenoid verrucous papules on the forearms and hands. Histopathology of the waxy papules exhibited deposition of periodic acid Schiff–positive basement membrane–like material in the superficial dermis, characteristic of LP. The verruca plana–like lesions exhibited acanthosis and enlarged keratinocytes with pale blue‐grey cytoplasm and a perinuclear halo, consistent with verrucae and EV. Polymerase chain reaction amplification and sequencing of ECM1, EVER1, and EVER2 demonstrated a homozygous point mutation, c.389C>T (p.Thr130Met), in exon 6 of ECM1 and a heterozygous point mutation, c.917 A>T (p.Asn306Ile), in exon 8 in EVER2, known to cause EV in homozygous patients. The homozygous point mutation c.389C>T in ECM1 may be a novel mutation causing LP. Verruca plana–like lesions seen in LP appear to represent a form of acquired EV. In this patient, a heterozygous mutation in EVER2 at c.917 A>T may also have conferred susceptibility to HPV infection.     

Biologie der Epidermodysplasia-verruciformis-assoziierten HPV

The genus betapapillomavirus (betaPV) presently comprises more than 40 virus types including the so-called epidermodysplasia verruciformis (EV)-associated HPV, which were originally detected in EV-patients by Southern blot hybridization. BetaPV are ubiquitous in the general population and frequently establish themselves already during the first weeks of life. Hair follicles are regarded as natural reservoir. About 25% of betaPV detected in adults persist for at least 9 months. Due to very low virus production, seroconversion against betaPV starts sluggishly. Hyperproliferation of keratinocytes in psoriasis patients or after severe burns stimulates virus replication. Massive virus replication only occurs in EV-patients, associated with the induction of disseminated skin lesions with a high risk of malignant conversion. In 75% of EV-patients this can be put down to homozygous, inactivating mutations in the genes EVER1 or EVER2. A transgenic mouse model substantiated the crucial role of increased HPV8 oncogene expression, induced by UV-irradiation or wounding, for tumor induction.     

Autosomal Dominant Epidermodysplasia Verruciformis Lacking a Known EVER1 or EVER2 Mutation

Abstract:  Epidermodysplasia verruciformis is a rare genodermatosis characterized by abnormal susceptibility to infection with specific human papillomavirus serotypes. Epidermodysplasia verruciformis is a genetically heterogeneous disease, and autosomal recessive and X-linked inheritance patterns have been reported. Nonsense mutations in the genes EVER1 and EVER2 have been identified in over 75% of cases. We present epidermodysplasia verruciformis in a father and a son with typical histologic and clinical findings that occur in the absence of mutations in EVER1 or EVER2. Epidermodysplasia verruciformis in this father/son pair in a nonconsanguinous pedigree is consistent with autosomal dominant inheritance. This is the first report of autosomal dominant transmission of epidermodysplasia verruciformis, providing further evidence of the genetic heterogeneity of epidermodysplasia verruciformis.     

Possible involvement of epidermodysplasia verruciformis human papillomaviruses in the immunopathogenesis of psoriasis: a proposed hypothesis

We have shown previously in psoriasis a very high prevalence of epidermodysplasia verruciforms-associated human papillomavirus 5 (EVHPV5) DNA and antibodies to human papillomavirus 5 (HPV5) virus-like particle (VLP) L1, and we suggested that this benign hyperproliferative disorder could be a reservoir for EVHPVs. Here we provide new data confirming the expression of EVHPVs in psoriasis and present our hypothesis on their possible involvement in the immunopathogenesis of the disorder. The new important finding was detection by radioimmunoprecipitation assay of a very high prevalence of antibodies to E6/E7 HPV5 oncoproteins, known to enhance keratinocyte proliferation. More recently, EV genes were identified, EVER1 and EVER2, whose mutations are responsible for epidermodysplasia verruciformis. Eidermodysplasia verruciforms-associated human papillomaviruses are harmless to the general population as a result of genetic restriction, which in psoriasis appears to be partly alleviated, and this may allow the viral gene expression. We hypothesize that induction of keratinocyte proliferation in psoriasis by various stimuli initiates the EVHPV life cycle with expression of early (E6/E7) and late (L1) viral proteins. The early proteins may, in turn, enhance the keratinocyte proliferation, and the late proteins could serve as target for specific-B- and T-cell-mediated responses. Immune responses against the viral antigens in the epidermis may result in the chemoattraction of leukocytes and Munro abscess formation, as well as in production of the psoriatic process. The novel immunomodulatory therapies could also inhibit immune responses against EVHPV proteins, leading to decreased cytokine production, keratinocyte proliferation and EVHPV expression. Thus the beneficial effect of these therapies is not discordant with the propose hypothesis of possible involvement of EVHPVs in the immunopathogenesis of psoriasis.     

耳聋-掌跖皮肤角化征家系GJB2基因突变分析

目的 观察耳聋-掌跖皮肤角化(PPK)综合征家系GJB2、GJB3和GJB6基因突变情况,探讨其基因型、表型和遗传学特征。方法 收集1例耳聋-掌跖皮肤角化征家系中先证者和部分亲属的临床资料,采集其外周血样本,并提取DNA。应用聚合酶链反应(PCR)扩增GJB2、GJB3和GJB6基因编码区,并以直接测序法进行突变分析;同时选取126人作为正常对照组。结果 先证者和父亲均携带GJB2基因R75W杂合突变,而GJB3和GJB6基因未见致病突变。正常对照组中未检测出R75W突变。结论 再次在中国人耳聋-掌跖皮肤角化征家系中发现GJB2基因R75W杂合突变,进一步验证了该突变可能是导致疾病发生的原因。R75W可能以显性方式由亲代遗传至子代,基因检查结果可为进一步生育指导提供帮助。     

结节性硬化症的基因突变研究

目的研究1例中国汉族人结节性硬化症TSC1和TSC2基因的突变情况。方法采用聚合酶链反应(PCR)扩增该例结节性硬化症患者、家族中的正常人以及100名健康对照者的TSC1和TSC2基因的全部外显子,并进行DNA测序分析。结果该例患者TSC1基因第15外显子存在C.1884-1887del AAAG(P.Leu628Leu fs X23)移码突变,引起读码框移位,并在其后第23位氨基酸处提前出现终止密码子TGA。家族中的正常成员及100名无关正常对照未检测出该位点突变。结论 TSC1基因的新缺失突变C.1884-1887del AAAG可能是导致患者临床发病的主要原因,该突变为新突变。     

角膜炎、鱼鳞病、耳聋综合征的GJB2基因突变研究

目的 检测国内首例先天性角膜炎、鱼鳞病、耳聋综合征(KID)患者的GJB2基因和GJB6基因突变.方法 提取KID综合征患者及家族成员的基因组DNA,采用聚合酶链反应扩增GJB2基因和GJB6基因所有的外显子及其邻近的剪切点,并进行双向直接测序.结果 KID综合征患者的GJB6基因未见变化,GJB2基因核苷酸序列exon2第148位碱基由G突变成A,导致蛋白第50位的天冬氨酸转换成天冬酰胺(D50N).结论 GJB2基因突变可能是本例角膜炎、鱼鳞病、耳聋综合征的致病基因.     

Identification of HLA antigens in familial and non-familial epidermodysplasia verruciformis

The distribution of HLA specificities was studied in 7 non-familial cases of epidermodysplasia verruciformis (EV) and in 5 cases from one family. In the non-familial cases, six antigens of locus A (2, 3, 9, 10, 24, 26) and eight antigens of locus B (7, 15, 27, 35, 37, 38, 40, 41) were found. All 5 cases of familial EV possessed 26,5 haplotype, however, 6 of the remaining 12 healthy family members inherited the same haplotype. There is no association of EV with HLA-A and B antigens. However, the defect of cell-mediated immunity, present in all EV cases, may indicate the association of the disease with other major histocompatibility products (i.e. loci on immune response genes).     

Confirmation and refinement of a genetic locus for disseminated superficial actinic porokeratosis (DSAP1) at 12q23.2-24.1

BACKGROUND: Our previous study has identified two loci for disseminated superficial actinic porokeratosis (DSAP), but the genes responsible are still unknown. OBJECTIVES: To narrow down the candidate regions and to assess candidate genes. METHODS: A genome-wide scan and linkage analysis were carried out in a newly collected five-generation Chinese family with DSAP. In addition, six candidate genes were screened for possible DSAP-associated mutations. RESULTS: DSAP in this family was associated with chromosome 12q. Fine mapping and haplotype construction refined the DSAP1 locus to a 4.4-cM interval. No disease-associated mutation was detected in CRY1, C4ST1, TXNRD1, HCF2, CMKLR1 or KIAA0789 genes. CONCLUSIONS: The DSAP1 locus was localized to a 4.4-cM interval at chromosome 12q23.2-24.1. CRY1, C4ST1, TXNRD1, HCF2, CMKLR1 and KIAA0789 genes were not associated with DSAP1.     

Keratin 17 mutation in pachyonychia congenita type 2 with early onset sebaceous cysts

BACKGROUND: Pachyonychia congenita (PC) is a group of autosomal dominant ectodermal dysplasias caused by mutations in four differentiation-specific keratin genes. Two major clinical subtypes of PC have been generally recognized. Symmetrically thickened fingernails and toenails are the defining characteristic of PC type 2 (PC-2) with onset at infancy. Pilosebaceous cysts are the best hallmark of PC-2, but they usually occur at puberty. OBJECTIVES: To report a Chinese pedigree of PC-2 with unusually early onset sebaceous cysts and to explore the genetic mutation and its phenotype. METHODS: Exon 1 of keratin 17 was amplified by polymerase chain reaction (PCR) from genomic DNA from the three patients in the pedigree, the proband, his half-sister and his younger son, two unaffected members in the pedigree and 50 unrelated and unaffected people. PCR products were directly sequenced to detect the mutation. RESULTS: Direct sequencing of the PCR products revealed a heterozygous 275A-->G mutation in all three affected members. This mutation predicts the substitution of asparagine by serine in codon 92 (N92S) located in the 1A domain of keratin 17. CONCLUSIONS: Mutation in the 1A domain of keratin 17 underlies the affected members' phenotype, PC-2 with early onset sebaceous cysts and late-onset thickened fingernails and toenails. The onset of the cysts is very early in some people within this family and the age at onset of thickened fingernails and toenails is variable within the family, implying the existence of modifying factors.     

Do epidermodysplasia verruciformis human papillomaviruses contribute to malignant and benign epidermal proliferations?

The aim of this review is to present new data on epidermodysplasia verruciformis (EV) and EV human papillomaviruses (HPVs), regarded previously as specific to the disease. Recently introduced highly sensitive molecular methods for virologic studies allow detection of EV HPVs in non-EV populations. In this article, we present the most recent findings on EV and EV HPVs, which shed new light on a possible contribution of EV viruses to malignant and benign epidermal proliferation. We discuss the significance of EV HPV DNA detection in premalignant cutaneous lesions and nonmelanoma skin cancers; however, direct evidence for the causative role of EV HPV is still not available. In psoriasis, a high frequency of EV HPV-5 and other EV HPVs in the skin and the presence of specific HPV-5 antibodies strongly suggest expression of EV HPV proteins in this extensive epidermal proliferation. Epidermodysplasia verruciformis HPV-5 may also be transiently expressed in epidermal repair processes, whereas in psoriasis there is a continuous epidermal proliferation that could result in persistent viral expression. A potential contribution of EV HPVs to the pathogenesis of psoriasis is also supported by the recently disclosed co-localization of susceptibility loci for psoriasis and EV in the same region of chromosome arm 17qter; however, specific genes for both conditions are still not identified.     

反常性痤疮一家系nicastrin基因突变研究

目的 研究一家系2例汉族反常性痤疮患者γ分泌酶基因的突变.方法 提取家系中5名成员(2例患者、先证者父亲、2例目前未发病者)的外周血DNA,扩增nicastrin蛋白(NCSTN)、早老素(PSEN)1、早老素增强子(PSENEN)、前咽缺陷蛋白(APH1)基因所有外显子和侧翼序列进行测序,并以100例无关系健康人作为对照.同时比较先证者皮损与4个健康对照NCSTN基因mRNA表达差异.结果 检测到2例患者血样DNA存在NCSTN基因中第477位碱基发生C→A的杂合突变,即c.477C＞A,其余3名家系成员及健康对照未发现相应突变;查询美国国家生物技术信息中心网站单核苷酸多态性数据库也未发现此突变.另外,先证者皮损NCSTN mRNA水平较健康对照明显减少.结论 NCSTN基因新的无义突变c.477C＞A是该反常性痤疮家系的致病突变,并可能通过无义介导的mRNA降解途径导致该基因功能失活.     

Evidence for a nonallelic heterogeneity of epidermodysplasia verruciformis with two susceptibility loci mapped to chromosome regions 2p21-p24 and 17q25

Epidermodysplasia verruciformis is a rare genodermatosis associated with a high risk of skin cancer. This condition is characterized by an abnormal susceptibility to specific related human papillomavirus genotypes, including the oncogenic HPV5. Epidermodysplasia verruciformis is usually considered as an autosomal recessive disease. We recently mapped a susceptibility locus for epidermodysplasia verruciformis (EV1) to chromosome 17qter within the 1 cM interval between markers D17S939 and D17S802. We report here the genotyping for 10 microsatellite markers spanning 29 cM around EV1 in two consanguineous epidermodysplasia verruciformis families from Colombia (C2) and France (F1) comprising five patients and two patients, respectively. Using homozygosity mapping, linkage with 17qter markers was observed for family C2 only. Multipoint linkage analysis yielded maximum multipoint LOD-score values above 10 between markers D17S1839 and D17S802 encompassing the EV1 locus. A genome-wide search performed in family F1 yielded evidence for linkage between epidermodysplasia verruciformis and the chromosomal 2p marker D2S365. Nine additional microsatellite markers spanning 15 cM in this region were analyzed. Assuming an autosomal recessive inheritance with a complete penetrance, the expected maximum two-point LOD-score value of 1.8 was obtained for three markers and multipoint linkage analysis yielded a maximum LOD-score value of 3. 51 between markers D2S2144 and D2S392. Haplotype analysis allowed to map a candidate region for a second epidermodysplasia verruciformis susceptibility locus (EV2) within the 8 cM interval between markers D2S171 and D2S2347 of the 2p21-p24 region. In contrast, linkage with 2p markers was excluded for family C2 and for the three families in which we mapped EV1 previously. The disclosure of two susceptibility loci for epidermodysplasia verruciformis provides evidence for a nonallelic heterogeneity in this disease.     

G59S mutation in the GJB2 gene in a Chinese family with classic Vohwinkel syndrome

Vohwinkel syndrome (VS) is a rare autosomal dominant condition, also known as mutilating palmoplantar keratoderma accompanied by sensorineural deafness. The LOR and GJB2 genes are reported to be responsible for VS. The GJB2 gene encodes connexin 26, a component of intercellular gap junctions expressed in various tissues. We report the case of a 31‐year‐old Chinese woman with classic VS characterized by sensorineural deafness and mutilating palmoplantar keratoderma. Further genetic studies demonstrated a nucleotide change (c.175G>A) in the GJB2 gene, leading to an amino acid alteration (G59S). This identical missense mutation (G59S) has also been reported in a patient with Bart–Pumphrey syndrome. Together with our findings and previous studies, we conclude that the identical mutation (G59S) in the GJB2 gene contributes to various manifestations.     

Heterogeneous mutations of the ATP2C1 gene causing Hailey–Hailey disease in Hong Kong Chinese

Background Hailey–Hailey disease (HHD) is a rare autosomal dominant dermatosis. It causes suprabasilar acantholysis leading to vesicular and crusted erosions affecting the flexures. Mutation of ATP2C1 gene encoding the human secretory pathway Ca²⁺/Mn²⁺‐ATPase (hSPCA1) was identified to be the cause of this entity. Objective The aim of this study was to study the mutational profile of the ATP2C1 gene in Hong Kong Chinese patients with HHD. Methods Patients with the clinical diagnosis of HHD proven by skin biopsy were included in this study. Mutation analysis was performed in 17 Hong Kong Chinese patients with HHD. Results Ten mutations in the ATP2C1 gene were found. Six of these were novel mutations. The novel mutations included a donor splice site mutation (IVS22+1G>A); a missense mutation (c.1049A>T); two deletion mutations (c.185_188delAGTT and c.923_925delAAG); an acceptor splice site mutation (IVS21‐1G>C) and an insertion mutation (c.2454dupT). Conclusion The six novel mutations provide additions to the HHD mutation database. No hot‐spot mutation was found and high allelic heterogeneity was demonstrated in the Hong Kong Chinese patients.     

Mutation L437P in the 2B domain of keratin 1 causes diffuse palmoplantar keratoderma in a Chinese pedigree

Diffuse palmoplantar keratoderma (DPPK) is an autosomal dominant genodermatosis characterized by uniform hyperkeratosis of the palm and sole epidermis. This disorder can be caused by mutations in the genes keratin 1 , keratin 9 , keratin 16 , desmoglein 1 and plakoglobin . Here we present a DPPK Chinese pedigree and identify the aetiology as a novel missense mutation, L437P, located in a highly conserved helix motif in domain 2B of KRT1. Functional analysis shows that overexpression of the L437P mutant in cultured cells leads to abnormal intermediate filament networks and filament aggregation. This gain-of-function mutation highlights the role of domain 2B in mediating filament assembly.

Conflicts of interest

The authors declare that they have no actual or potential conflicts of interest to disclose. Appropriate approval and procedures were used concerning human subjects.     

一个表皮松解性掌跖角化病家系的KRT1基因突变分析

目的 探讨一个中国汉族人表皮松解性掌跖角化病(EPPK)家系的角蛋白基因KRT1、KRT9、KRT10突变情况.方法 收集1个EPPK家系的临床资料,提取外周血DNA,通过PCR扩增角蛋白KRT1、KRT9、KRT10基因编码区的全部外显子及其侧翼序列并测序,以表型正常家系成员及50例健康人为正常对照.结果 发现家系内6例患者均存在KRT1基因错义突变c.1436T>C,导致第479位的异亮氨酸被苏氨酸取代(I479T),在家系中6例正常人及50例对照者未发现上述突变.结论 错义突变KRTI的c.1436T>C可能为导致该家系临床表型的主要原因.本例为国内首次发现的KRT1突变引起的EPPK家系.

Abstract：

Objective To analyze the mutations in keratin 1 (KRT1), KRT9 and KRT10 genes in a Chinese family with epidermolytic palmoplantar keratoderma (EPPK). Methods Clinical data were collected from a family with EPPK. Genomic DNA was extracted from the peripheral blood of 12 family members, including 6 patients and 6 unaffected members, as well as from 50 unrelated normal human controls. PCR was performed to amplify all the exons and flanking sequences of KRT1, KRT9 and KRT10 genes followed by DNA sequencing.Results A missense mutation C.1436T > C was found in the highly conserved helix termination motif of KRT1 gene of all the patients, resulting in a substitution of isoleucine by threonine at position 479 of the KRT1 protein. No mutation was found in the unaffected members or unrelated controls. Conclusions The missense mutation C.1436T > C in K.RT1 gene is likely to be the main cause of the phenotype of EPPK in this family.This is the first report of a pedigree with KRT1 gene mutation-induced EPPK in China.