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C17-sphinganine analog mycotoxin (C17-SAMT) has been characterized as the contaminant responsible for the atypical toxicity reported in mussels from the Bizerte lagoon (northern Tunisia) over the past decade. C17-SAMT exhibited common symptoms of toxicity in mice, including flaccid paralysis and severe respiratory distress, followed by rapid death. To determine the potential health risks of this neurotoxin, we assessed its subchronic toxicity according to the recommendations of OCDE n° 407. The body weight and the structural changes of vital organs were recorded. Biochemical and hematological parameters were also quantified. Macroscopic observations showed that mice treated with 0.9, 9, and 90 µg/kg C17-SAMT had significantly reduced stomach weights, swollen and fragile intestines, and signs of nephritis with renal abscesses. Transaminase assays pointed out that exposure to C17-SAMT can lead to transaminitis. Above-average lactate dehydrogenase values were recorded in both the treated and satellite groups. Hematology data showed a significant reduction in red blood cell counts in high-dose-treated group. Reductions in hemoglobin and hematocrit were also recorded. Mean leukocyte counts were significantly elevated in the high-, mid-dose treated and satellite groups. At the microscopic level, we noted myocardial atrophy and hyperemia. In the lungs, we noted necrosis associated with macrophages perivascular infiltration and congestion. The kidneys showed mild inflammation and glomerular atrophy. The stomach exhibited mucosal atrophy, while a thin colon and distended small intestine were observed in high-dose-treated group. The liver was affected by vascular congestion, inflammatory infiltration, and lobular necrosis that evolved into acute hepatitis. Lesions, such as inflammatory infiltration and mild necrosis of the liver, cortical abscess with central necrosis in the kidney, and mild congestion of cardiac tissue were recorded in the satellite group.
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Nefropatias , Micotoxinas , Camundongos , Animais , Fígado/patologia , Nefropatias/patologia , Toxinas Marinhas , Necrose/patologiaRESUMO
Molecular diagnosis of rare inherited palmoplantar keratoderma (PPK) is still challenging. We investigated at the clinical and genetic level a consanguineous Tunisian family presenting an autosomal dominant atypical form of transgrediens and progrediens PPK to better characterize this ultrarare disease and to identify its molecular etiology. Whole-exome sequencing (WES), filtering strategies, and bioinformatics analysis have been achieved. Clinical investigation and follow up over 13 years of this Tunisian family with three siblings formerly diagnosed as an autosomal recessive form of Mal de Melela-like conducted us to reconsider its initial phenotype. Indeed, the three patients presented clinical features that overlap both Mal de Meleda and progressive symmetric erythrokeratoderma (PSEK). The mode of inheritance was also reconsidered, since the mother, initially classified as unaffected, exhibited a similar expression of the disease. WES analysis showed the absence of potentially functional rare variants in known PPKs or PSEK-related genes. Results revealed a novel heterozygous nonsynonymous variant in cadherin-12 gene (CDH12, NM_004061, c.1655C > A, p.Thr552Asn) in all affected family members. This variant is absent in dbSNP and in 50 in-house control exomes. In addition, in silico analysis of the mutated 3D domain structure predicted that this variant would result in cadherin-12 protein destabilization and thermal instability. Functional annotation and biological network construction data provide further supporting evidence for the potential role of CDH12 in the maintenance of skin integrity. Taken together, these results suggest that CDH12 gene is a potential candidate gene for an atypical presentation of an autosomal dominant form of transgrediens and progrediens PPK.
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Caderinas , Transtornos Cromossômicos , Eritroceratodermia Variável , Genes Dominantes , Mutação de Sentido Incorreto , Adulto , Idoso , Proteínas Relacionadas a Caderinas , Caderinas/química , Caderinas/genética , Transtornos Cromossômicos/genética , Transtornos Cromossômicos/patologia , Simulação por Computador , Eritroceratodermia Variável/genética , Eritroceratodermia Variável/patologia , Feminino , Humanos , Masculino , Domínios Proteicos , Pele/patologia , Sequenciamento do ExomaRESUMO
BACKGROUND: A family history of breast cancer has long been thought to indicate the presence of inherited genetic events that predispose to this disease. In North Africa, many specific epidemio-genetic characteristics have been observed in breast cancer families when compared to Western populations. Despite these specificities, the majority of breast cancer genetics studies performed in North Africa remain restricted to the investigation of the BRCA1 and BRCA2 genes. Thus, comprehensive data at a whole exome or whole genome level from local patients are lacking. METHODS: A whole exome sequencing (WES) of seven breast cancer Tunisian families have been performed using a family-based approach. We focused our analysis on BC-TN-F001 family that included two affected members that have been sequenced using WES. Relevant variants identified in BC-TN-F001 have been confirmed using Sanger sequencing. Then, we conducted an integrative analysis by combining our results with those from other WES studies in order to figure out the genetic transmission model of the newly identified genes. Biological network construction and protein-protein interactions analyses have been performed to decipher the molecular mechanisms likely accounting for the role of these genes in breast cancer risk. RESULTS: Sequencing, filtering strategies, and validation analysis have been achieved. For BC-TN-F001, no deleterious mutations have been identified on known breast cancer genes. However, 373 heterozygous, exonic and rare variants have been identified on other candidate genes. After applying several filters, 12 relevant high-risk variants have been selected. Our results showed that these variants seem to be inherited in a family specific model. This hypothesis has been confirmed following a thorough analysis of the reported WES studies. Enriched biological process and protein-protein interaction networks resulted in the identification of four novel breast cancer candidate genes namely MMS19, DNAH3, POLK and KATB6. CONCLUSIONS: In this first WES application on Tunisian breast cancer patients, we highlighted the impact of next generation sequencing technologies in the identification of novel breast cancer candidate genes which may bring new insights into the biological mechanisms of breast carcinogenesis. Our findings showed that the breast cancer predisposition in non-BRCA families may be ethnic and/or family specific.
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Neoplasias da Mama/genética , Sequenciamento do Exoma , Predisposição Genética para Doença , Alelos , Neoplasias da Mama/epidemiologia , Família , Feminino , Genes Neoplásicos , Estudos de Associação Genética , Variação Genética , Humanos , Masculino , Linhagem , Mapas de Interação de Proteínas , TunísiaRESUMO
BACKGROUND: Breast cancer is the most common cancer in women worldwide. Around 50% of breast cancer familial risk has been so far explained by known susceptibility alleles with variable levels of risk and prevalence. The vast majority of these breast cancer associated variations reported to date are from populations of European ancestry. In spite of its heterogeneity and genetic wealth, North-African populations have not been studied by the HapMap and the 1000Genomes projects. Thus, very little is known about the genetic architecture of these populations. METHODS: This study aimed to investigate a subset of common breast cancer loci in the general Tunisian population and to compare their genetic composition to those of other ethnic groups. We undertook a genome-wide haplotype study by genotyping 135 Tunisian subjects using the Affymetrix 6.0-Array. We compared Tunisian allele frequencies and linkage disequilibrium patterns to those of HapMap populations and we performed a comprehensive assessment of the functional effects of several selected variants. RESULTS: Haplotype analyses showed that at risk haplotypes on 2p24, 4q21, 6q25, 9q31, 10q26, 11p15, 11q13 and 14q32 loci are considerably frequent in the Tunisian population (> 20%). Allele frequency comparison showed that the frequency of rs13329835 is significantly different between Tunisian and all other HapMap populations. LD-blocks and Principle Component Analysis revealed that the genetic characteristics of breast cancer variants in the Tunisian, and so probably the North-African populations, are more similar to those of Europeans than Africans. Using eQTl analysis, we characterized rs9911630 as the most strongly expression-associated SNP that seems to affect the expression levels of BRCA1 and two long non coding RNAs (NBR2 and LINC008854). Additional in-silico analysis also suggested a potential functional significance of this variant. CONCLUSIONS: We illustrated the utility of combining haplotype analysis in diverse ethnic groups with functional analysis to explore breast cancer genetic architecture in Tunisia. Results presented in this study provide the first report on a large number of common breast cancer genetic polymorphisms in the Tunisian population which may establish a baseline database to guide future association studies in North Africa.
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População Negra/genética , Neoplasias da Mama/genética , Loci Gênicos/genética , Predisposição Genética para Doença , Estudo de Associação Genômica Ampla , Adulto , Simulação por Computador , Feminino , Frequência do Gene/genética , Haplótipos/genética , Voluntários Saudáveis , Humanos , Desequilíbrio de Ligação/genética , Masculino , Pessoa de Meia-Idade , Polimorfismo de Nucleotídeo Único , TunísiaRESUMO
Precision Medicine is being increasingly used in the developed world to improve health care. While several Precision Medicine (PM) initiatives have been launched worldwide, their implementations have proven to be more challenging particularly in low- and middle-income countries. To address this issue, the "Personalized Medicine in North Africa" initiative (PerMediNA) was launched in three North African countries namely Tunisia, Algeria and Morocco. PerMediNA is coordinated by Institut Pasteur de Tunis together with the French Ministry for Europe and Foreign Affairs, with the support of Institut Pasteur in France. The project is carried out along with Institut Pasteur d'Algérie and Institut Pasteur du Maroc in collaboration with national and international leading institutions in the field of PM including Institut Gustave Roussy in Paris. PerMediNA aims to assess the readiness level of PM implementation in North Africa, to strengthen PM infrastructure, to provide workforce training, to generate genomic data on North African populations, to implement cost effective, affordable and sustainable genetic testing for cancer patients and to inform policy makers on how to translate research knowledge into health products and services. Gender equity and involvement of young scientists in this implementation process are other key goals of the PerMediNA project. In this paper, we are describing PerMediNA as the first PM implementation initiative in North Africa. Such initiatives contribute significantly in shortening existing health disparities and inequities between developed and developing countries and accelerate access to innovative treatments for global health.
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Significant advances have been made to understand the genetic basis of breast cancer. High, moderate and low penetrance variants have been identified with inter-ethnic variability in mutation frequency and spectrum. Genome wide association studies (GWAS) are widely used to identify disease-associated SNPs. Understanding the functional impact of these risk-SNPs will help the translation of GWAS findings into clinical interventions. Here we aim to characterize the genetic patterns of high and moderate penetrance breast cancer susceptibility genes and to assess the functional impact of non-coding SNPs. We analyzed BRCA1/2, PTEN, STK11, TP53, ATM, BRIP1, CHEK2 and PALB2 genotype data obtained from 135 healthy participants genotyped using Affymetrix Genome-Wide Human SNP-Array 6.0. Haplotype analysis was performed using Haploview.V4.2 and PHASE.V2.1. Population structure and genetic differentiation were assessed using principal component analysis (PCA) and fixation index (FST). Functional annotation was performed using In Silico web-based tools including RegulomeDB and VARAdb. Haplotype analysis showed distinct LD patterns with high levels of recombination and haplotype blocks of moderate to small size. Our findings revealed also that the Tunisian population tends to have a mixed origin with European, South Asian and Mexican footprints. Functional annotation allowed the selection of 28 putative regulatory variants. Of special interest were BRCA1_ rs8176318 predicted to alter the binding sites of a tumor suppressor miRNA hsa-miR-149 and PALB2_ rs120963 located in tumorigenesis-associated enhancer and predicted to strongly affect the binding of P53. Significant differences in allele frequencies were observed with populations of African and European ancestries for rs8176318 and rs120963 respectively. Our findings will help to better understand the genetic basis of breast cancer by guiding upcoming genome wide studies in the Tunisian population. Putative functional SNPs may be used to develop an efficient polygenic risk score to predict breast cancer risk leading to better disease prevention and management.
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Neoplasias da Mama , MicroRNAs , Neoplasias da Mama/epidemiologia , Neoplasias da Mama/genética , Feminino , Frequência do Gene , Predisposição Genética para Doença , Estudo de Associação Genômica Ampla , Humanos , Penetrância , Polimorfismo de Nucleotídeo ÚnicoRESUMO
There are limited national population-based studies on HPV genotypes distribution in Tunisia, thus making difficult an assessment of the burden of vaccine-preventable cervical cancer. In this context, we conducted a national survey to determine the HPV prevalence and genotypes distribution and the risk factors for HPV infections in Tunisian women. This is a cross-sectional study performed between December 2012 and December 2014. A liquid-based Pap smear sample was obtained from all women and samples' DNAs were extracted. Only women with betaglobin-positive PCR were further analysed for HPV detection and typing by a nested-PCR of the L1 region followed by next-generation sequencing. A multiple logistic regression model was used for the analysis of associations between the variables. A total of 1517 women were enrolled in this study, and 1229 out of the 1517 cervical samples were positive for the betaglobin control PCR and tested for HPV. Overall HPV infection prevalence was measured to be 7.8% (96/1229), with significant differences between the grand regions, ranging from 2% in the North to 13.1% in Grand Tunis. High-risk HPV genotypes accounted for 5% of the infections. The most prevalent genotypes were HPV 31 (1%), 16 (0.9%), 59 (0.7%). HPV18 was detected only in four cases of the study population. Potential risk factors were living in Grand Tunis region (OR: 7.94 [2.74-22.99]), married status (OR: 2.74 [1.23-6.13]), smoking habit (OR: 2.73 [1.35-5.51]), occupation (OR: 1.81 [1.09-3.01]) and women with multiple sexual partners (OR: 1.91 [1.07-3.39]). These findings underscore the need to evaluate the cost effectiveness of HPV vaccine implementation, contribute to the evidence on the burden of HPV infections, the critical role of sexual behaviour and socioeconomic status, and call for increased support to the preventive program of cervical cancer in Tunisia.
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Alphapapillomavirus , Infecções por Papillomavirus , Vacinas contra Papillomavirus , Neoplasias do Colo do Útero , Humanos , Feminino , Papillomaviridae/genética , Prevalência , Estudos Transversais , Tunísia/epidemiologia , Genótipo , Fatores de RiscoRESUMO
Several syndromic forms of digestive cancers are known to predispose to early-onset gastric tumors such as Hereditary Diffuse Gastric Cancer (HDGC) and Lynch Syndrome (LS). LSII is an extracolonic cancer syndrome characterized by a tumor spectrum including gastric cancer (GC). In the current work, our main aim was to identify the mutational spectrum underlying the genetic predisposition to diffuse gastric tumors occurring in a Tunisian family suspected of both HDGC and LS II syndromes. We selected the index case "JI-021", which was a woman diagnosed with a Diffuse Gastric Carcinoma and fulfilling the international guidelines for both HDGC and LSII syndromes. For DNA repair, a custom panel targeting 87 candidate genes recovering the four DNA repair pathways was used. Structural bioinformatics analysis was conducted to predict the effect of the revealed variants on the functional properties of the proteins. DNA repair genes panel screening identified two variants: a rare MSH2 c.728G>A classified as a variant with uncertain significance (VUS) and a novel FANCD2 variant c.1879G>T. The structural prediction model of the MSH2 variant and electrostatic potential calculation showed for the first time that MSH2 c.728G>A is likely pathogenic and is involved in the MSH2-MLH1 complex stability. It appears to affect the MSH2-MLH1 complex as well as DNA-complex stability. The c.1879G>T FANCD2 variant was predicted to destabilize the protein structure. Our results showed that the MSH2 p.R243Q variant is likely pathogenic and is involved in the MSH2-MLH1 complex stability, and molecular modeling analysis highlights a putative impact on the binding with MLH1 by disrupting the electrostatic potential, suggesting the revision of its status from VUS to likely pathogenic. This variant seems to be a shared variant in the Mediterranean region. These findings emphasize the importance of testing DNA repair genes for patients diagnosed with diffuse GC with suspicion of LSII and colorectal cancer allowing better clinical surveillance for more personalized medicine.
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Carcinoma , Síndrome de Lynch II , Neoplasias Gástricas , Reparo de Erro de Pareamento de DNA , Feminino , Mutação em Linhagem Germinativa , Humanos , Proteína 2 Homóloga a MutS/genética , Neoplasias Gástricas/diagnóstico , Neoplasias Gástricas/genética , TunísiaRESUMO
Hereditary breast cancer accounts for 5-10% of all breast cancer cases. So far, known genetic risk factors account for only 50% of the breast cancer genetic component and almost a quarter of hereditary cases are carriers of pathogenic mutations in BRCA1/2 genes. Hence, the genetic basis for a significant fraction of familial cases remains unsolved. This missing heritability may be explained in part by Copy Number Variations (CNVs). We herein aimed to evaluate the contribution of CNVs to hereditary breast cancer in Tunisia. Whole exome sequencing was performed for 9 BRCA negative cases with a strong family history of breast cancer and 10 matched controls. CNVs were called using the ExomeDepth R-package and investigated by pathway analysis and web-based bioinformatic tools. Overall, 483 CNVs have been identified in breast cancer patients. Rare CNVs affecting cancer genes were detected, of special interest were those disrupting APC2, POU5F1, DOCK8, KANSL1, TMTC3 and the mismatch repair gene PMS2. In addition, common CNVs known to be associated with breast cancer risk have also been identified including CNVs on APOBECA/B, UGT2B17 and GSTT1 genes. Whereas those disrupting SULT1A1 and UGT2B15 seem to correlate with good clinical response to tamoxifen. Our study revealed new insights regarding CNVs and breast cancer risk in the Tunisian population. These findings suggest that rare and common CNVs may contribute to disease susceptibility. Those affecting mismatch repair genes are of interest and require additional attention since it may help to select candidates for immunotherapy leading to better outcomes.
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Proteína BRCA1/genética , Proteína BRCA2/genética , Neoplasias da Mama/genética , Mutação em Linhagem Germinativa , Adulto , Neoplasias da Mama/epidemiologia , Variações do Número de Cópias de DNA , Feminino , Genes BRCA1 , Genes BRCA2 , Predisposição Genética para Doença , Humanos , Pessoa de Meia-Idade , Tunísia/epidemiologiaRESUMO
Nucleotide excision repair is a multistep process that recognizes and eliminates a spectrum of DNA damages. Five proteins, namely XPC, RAD23, Centrin 2, DDB1 and DDB2 act as a heterodimeric complex at the early steps of the NER pathway and play a crucial role in the removal of DNA lesions. Several exonic mutations on genes coding for these proteins have been identified as associated with Xeroderma-pigmentosum (XP), a rare monogenic disorder. However, the role of regulatory polymorphisms in disease development and inter-ethnic diversity is still not well documented. Due to the high incidence rate of XP in Tunisia, we performed a genotyping analysis of 140 SNPs found on these 5 genes in a set of 135-subjects representing the general Tunisian-population. An inter-ethnic comparison based on the genotype frequency of these SNPs have been also conducted. For the most relevant variants, we performed a comprehensive assessment of their functional effects. Linkage disequilibrium and principal component analysis showed that the Tunisian-population is an admixed and intermediate population between Sub-Saharan Africans and Europeans. Using variable factor maps, we identified a list of 20 polymorphisms that contribute considerably to the inter-ethnic diversity of the NER complex. In-silico functional analysis showed that SNPs on XPC, DDB1 and DDB2 are associated with eQTLs mainly DDB2-rs10838681 that seems to decrease significantly the expression level of ACP2 (p = 6.1 × 10-26). Statistical analysis showed that the allelic frequency of DDB2-rs10838681 in Tunisia is significantly different from all other populations. Using rVarBase, we identified 5 variants on XPC, DDB1 and DDB2 that seem to alter the binding sites of several transcription factors considered as key players in DNA-repair pathways. Results presented in this study provide the first report on regulatory polymorphisms of the NER-complex genes in Tunisia. These results may also help to establish a baseline database for future association and functional studies.
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Biologia Computacional/métodos , Reparo do DNA , Redes Reguladoras de Genes , Polimorfismo de Nucleotídeo Único , Xeroderma Pigmentoso/genética , Fosfatase Ácida/genética , Proteínas de Ligação ao Cálcio/genética , Proteínas de Ciclo Celular/genética , Simulação por Computador , Enzimas Reparadoras do DNA/genética , Proteínas de Ligação a DNA/genética , Feminino , Humanos , Desequilíbrio de Ligação , Masculino , Tunísia/etnologia , Xeroderma Pigmentoso/etnologiaRESUMO
INTRODUCTION: Zoonotic cutaneous leishmaniasis (ZCL), due to infection by Leishmania (L). major, is characterized by polymorphic clinical manifestations which could be attributed to the host's immune response. In this study we investigated the involvement of cytotoxic cells on the outcome of the disease. METHODS: Expression of granzyme B (GrB), granulysine (Grly), and interferon (IFN)-γ was evaluated within ZCL lesion specimens using the technique of real-time quantitative polymerase chain reaction (RT-qPCR). Immunohistochemical staining was performed using anti-CD3, CD4, CD8, CD56, GrB, and IFN-γ antibodies to identify the phenotype of GrB and IFN-γ-producing cells. RESULTS: GrB and Grly mRNA was detected within 75% and 80% of ZCL lesions, respectively. Statistical analysis demonstrated a significant correlation between levels of GrB and Grly. Interestingly, expression of these molecules correlates negatively with the lesion's age. The highest levels were measured in early lesions (E-ZCL) (lesion age ≤1 month) comparing to late lesions (L-ZCL) (lesion age >1 month). Otherwise, IFN-γ mRNA was detected only within 56% and a positive correlation was found between levels of this cytokine and those of GrB. Immunohistochemical analysis showed that GrB is produced essentially by CD8+ T cells whereas IFN-γ is produced by both CD4+ and CD8+ T cells. CONCLUSION: Together our results demonstrate the presence of cytotoxic cells producing GrB and Grly within leishmaniasis cutaneous lesions.
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Leishmania major/imunologia , Leishmaniose Cutânea/imunologia , Linfócitos T Citotóxicos/imunologia , Zoonoses/imunologia , Adulto , Animais , Antígenos de Diferenciação de Linfócitos T/genética , Antígenos de Diferenciação de Linfócitos T/imunologia , Antígenos de Diferenciação de Linfócitos T/metabolismo , Criança , Pré-Escolar , Citocinas/imunologia , Citocinas/metabolismo , Feminino , Expressão Gênica/imunologia , Granzimas/genética , Granzimas/imunologia , Granzimas/metabolismo , Humanos , Lactente , Recém-Nascido , Interferon gama/genética , Interferon gama/metabolismo , Leishmania major/parasitologia , Leishmaniose Cutânea/metabolismo , Leishmaniose Cutânea/parasitologia , Ativação Linfocitária/genética , Ativação Linfocitária/imunologia , Masculino , Pessoa de Meia-Idade , Pele/imunologia , Pele/parasitologia , Linfócitos T Citotóxicos/metabolismo , Zoonoses/parasitologiaRESUMO
Lesion features in cutaneous leishmaniasis (CL) depend on the infecting Leishmania species as well as on host immune reponse. In this study, we evaluated the histological and immunological differences between two forms of CL described in Tunisia: zoonotic cutaneous leishmaniasis (ZCL) caused by L. major and sporadic cutaneous leishmaniasis (SCL) caused by L. infantum. Histological analysis showed a mild to moderate infiltrate within ZCL lesions. In contrast, massive infiltration of the dermis was observed within SCL lesions. Contrary to ZCL, infiltrates within SCL lesions were organized and showed granuloma composed of macrophages and lymphocytes. In addition, immunohistochemical analysis showed a predominance of CD4+ T cells within both CL forms. Furthermore, expression of interferon-γ, interleukin (IL)-10, IL-8, IL-13 and monocyte chemotactic protein (MCP)-1 was evaluated using real-time quantitative polymerase chain reaction (RT-qPCR). MCP-1 and IL-10 were expressed at comparable levels in ZCL and SCL lesions. Interestingly, IL-8 mRNA levels were significantly higher in ZCL lesions compared to SCL lesions, but interferon-γ was significantly higher in SCL lesions than in ZCL lesions.
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Leishmania infantum , Leishmania major , Leishmaniose Cutânea/imunologia , Leishmaniose Cutânea/parasitologia , Pele/imunologia , Pele/parasitologia , Adolescente , Adulto , Idoso , Animais , Biópsia , Linfócitos T CD4-Positivos/imunologia , Criança , Derme/imunologia , Derme/parasitologia , Feminino , Granuloma/imunologia , Técnicas Histológicas , Humanos , Imuno-Histoquímica , Interferon gama/imunologia , Interleucinas/imunologia , Macrófagos/imunologia , Masculino , Pessoa de Meia-Idade , Pele/patologia , Tunísia , Adulto Jovem , Zoonoses/epidemiologia , Zoonoses/imunologia , Zoonoses/parasitologiaRESUMO
Dystrophic epidermolysis bullosa (DEB) is a group of heritable bullous skin disorders caused by mutations in the COL7A1 gene. One of the most severe forms of DEB is the severe generalized [recessive dystrophic epidermolysis bullosa (RDEB-SG)] subtype, which is inherited in an autosomal recessive manner. This subtype is most often due to COL7A1 mutations resulting in a premature termination codon on both alleles. We report here, the molecular investigation of 15 patients belonging to 14 nuclear families from the city of Sfax in Southern Tunisia, with clinical features of RDEB-SG complicated by squamous cell carcinoma in 3 patients. We identified two novel mutations, p.Val769LeufsX1 and p.Ala2297SerfsX91, in addition to one previously reported mutation (p.Arg2063Trp). The p.Val769LeufsX1 mutation was shared by 11 families and haplotype analysis indicated that it is a founder mutation. The p.Ala2297SerfsX91 mutation was a private mutation found in only one family. Together with the previously described recurrent mutations in Tunisia, screening for the founder p.Val769LeufsX1 mutation should provide a rapid molecular diagnosis tool for mutation screening in RDEB patients from Southern Tunisia and possibly from other Mediterranean populations sharing the same genetic background.
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Colágeno Tipo VII/genética , Epidermólise Bolhosa Distrófica/genética , Efeito Fundador , Alelos , Carcinoma de Células Escamosas/complicações , Códon sem Sentido/genética , Consanguinidade , Análise Mutacional de DNA , Epidermólise Bolhosa Distrófica/patologia , Feminino , Genes Recessivos , Haplótipos , Humanos , Masculino , Mutação , Linhagem , Pele/patologia , TunísiaRESUMO
Xeroderma pigmentosum Variant (XP-V) form is characterized by a late onset of skin symptoms. Our aim is the clinical and genetic investigations of XP-V Tunisian patients in order to develop a simple tool for early diagnosis. We investigated 16 suspected XP patients belonging to ten consanguineous families. Analysis of the POLH gene was performed by linkage analysis, long range PCR, and sequencing. Genetic analysis showed linkage to the POLH gene with a founder haplotype in all affected patients. Long range PCR of exon 9 to exon 11 showed a 3926 bp deletion compared to control individuals. Sequence analysis demonstrates that this deletion has occurred between two Alu-Sq2 repetitive sequences in the same orientation, respectively, in introns 9 and 10. We suggest that this mutation POLH NG_009252.1: g.36847_40771del3925 is caused by an equal crossover event that occurred between two homologous chromosomes at meiosis. These results allowed us to develop a simple test based on a simple PCR in order to screen suspected XP-V patients. In Tunisia, the prevalence of XP-V group seems to be underestimated and clinical diagnosis is usually later. Cascade screening of this founder mutation by PCR in regions with high frequency of XP provides a rapid and cost-effective tool for early diagnosis of XP-V in Tunisia and North Africa.
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Sequência de Bases , DNA Polimerase Dirigida por DNA/genética , Efeito Fundador , Haplótipos , Deleção de Sequência , Xeroderma Pigmentoso/genética , Adolescente , Adulto , Criança , Pré-Escolar , Éxons , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Tunísia , Xeroderma Pigmentoso/diagnóstico , Xeroderma Pigmentoso/terapiaRESUMO
Mal de Meleda (MDM) is a rare, autosomal recessive form of palmoplantar keratoderma. It is characterized by erythema and hyperkeratosis of the palms and soles that progressively extend to the dorsal surface of the hands and feet. It is caused by mutations in SLURP-1 gene encoding for secreted mammalian Ly-6/uPAR-related protein 1 (SLURP-1). We performed mutational analysis by direct sequencing of SLURP-1 gene in order to identify the genetic defect in three unrelated families (families MDM-12, MDM-13, and MDM-14) variably affected with transgressive palmoplantar keratoderma. A spectrum of clinical presentations with variable features has been observed from the pronounced to the transparent hyperkeratosis. We identified the 82delT frame shift mutation in the SLURP-1 gene in both families MDM-12 and MDM-13 and the missense variation p.Cys99Tyr in family MDM-14. To date, the 82delT variation is the most frequent cause of MDM in the world which is in favour of a recurrent molecular defect. The p.Cys99Tyr variation is only described in Tunisian families making evidence of founder effect mutation of likely Tunisian origin. Our patients presented with very severe to relatively mild phenotypes, including multiple keratolytic pits observed for one patient in the hyperkeratotic area which was not previously reported. The phenotypic variability may reflect the influence of additional factors on disease characteristics. This report further expands the spectrum of clinical phenotypes associated with mutations in SLURP1 in the Mediterranean population.
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Antígenos Ly/genética , Efeito Fundador , Mutação da Fase de Leitura/genética , Ceratodermia Palmar e Plantar/genética , Ativador de Plasminogênio Tipo Uroquinase/genética , Análise Mutacional de DNA , Sequenciamento de Nucleotídeos em Larga Escala , Humanos , Ceratodermia Palmar e Plantar/patologia , Região do Mediterrâneo , Linhagem , Fenótipo , TunísiaRESUMO
Xeroderma Pigmentosum (XP) is a rare recessive autosomal cancer prone disease, characterized by UV hypersensitivity and early appearance of cutaneous and ocular malignancies. We investigated four unrelated patients suspected to be XP-C. To confirm linkage to XPC gene, genotyping and direct sequencing of XPC gene were performed. Pathogenic effect of novel mutations was confirmed by reverse Transciptase PCR. Mutation screening revealed the presence of two novel mutations g.18246G>A and g.18810G>T in the XPC gene (NG_011763.1). The first is present in one patient XP50NEF, but the second is present in three unrelated patients (XP16KEB, XP28SFA, and XP45GB). These 3 patients are from three different cities of Southern Tunisia and bear the same haplotype, suggesting a founder effect. Reverse Transciptase PCR revealed the absence of the XPC mRNA. In Tunisia, as observed in an other severe genodermatosis, the mutational spectrum of XP-C group seems to be homogeneous with some clusters of heterogeneity that should be taken into account to improve molecular diagnosis of this disease.
Assuntos
Proteínas de Ligação a DNA/genética , Etnicidade/genética , Heterogeneidade Genética , Predisposição Genética para Doença , Mutação/genética , Adolescente , Criança , Pré-Escolar , Eletroforese em Gel de Ágar , Família , Feminino , Loci Gênicos/genética , Haplótipos/genética , Humanos , Masculino , Repetições de Microssatélites/genética , Linhagem , Tunísia , Adulto JovemRESUMO
Envenomation caused by Hemiscorpius (H.) lepturus from Liochlidae family presents clinical features that have not been previously described for the Buthidae family scorpions. The most significant manifestations of H. lepturus envenomation are hemolysis and dermonecrosis which could lead in severe cases to renal, cardio-respiratory failure, and death. In this study, we aimed to identify and characterize the protein(s) causing these effects. We have purified a 33 kDa protein from the venom of H. lepturus and named it Heminecrolysin. Tryptic digestion and MS/MS analysis of obtained peptides showed homology with previously described brown spider sphingomyelinases D. Functional characterization of Heminecrolysin indicated a sphingomyelinase D, a complement-dependent hemolysis properties and a dermonecrosis activity. Heminecrolysin displayed higher hemolytic activity to human erythrocytes (ED50 of 0.025 µg/ml), a stronger inflammatory and dermonecrotic effects when injected intra-dermally to rabbit skins, while its efficiency to hydrolyze sphingomyelin seems weaker than other known spider dermonecrotic SMasesD (149 ± 32.5 nmol/mg). Step of sensitization of human erythrocytes by Heminecrolysin was shown to be Mg²âº and Ca²âº-independent while hemolysis step in the presence of complement required both bivalent ions. Heminecrolysin is the first hemolytic dermonecrotic toxin identified in venom other than spiders. Except in spider Loxosceles genus and some pathogenic strains of Corynebacteria, sphingomyelinase D activity is unknown in the animal kingdom.