Publications (7)17.3 Total impact
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Article: Mutational analysis of the mitochondrial 12S rRNA and tRNASer(UCN) genes in Tunisian patients with nonsyndromic hearing loss.
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ABSTRACT: We explored the mitochondrial 12S rRNA and the tRNASer(UCN) genes in 100 Tunisian families affected with NSHL and in 100 control individuals. We identified the mitochondrial A1555G mutation in one out of these 100 families and not in the 100 control individuals. Members of this family harbouring the A1555G mutation showed phenotypic heterogeneity which could be explained by an eventual nuclear-mitochondrial interaction. So, we have screened three nuclear genes: GJB2, GJB3, and GJB6 but we have not found correlation between the phenotypic heterogeneity and variants detected in these genes. We explored also the entire mitochondrial 12S rRNA and the tRNASer(UCN) genes. We detected five novel polymorphisms: T742C, T794A, A813G, C868T, and C954T, and 12 known polymorphisms in the mitochondrial 12S rRNA gene. None of the 100 families or the 100 controls were found to carry mutations in the tRNASer(UCN) gene. We report here the first mutational screening of the mitochondrial 12S rRNA and the tRNASer(UCN) genes in the Tunisian population which describes the second family harbouring the A1555G mutation in Africa and reveals novel polymorphisms in the mitochondrial 12S rRNA gene.Biochemical and Biophysical Research Communications 03/2006; 340(4):1251-8. · 2.48 Impact Factor -
Article: Various 30 and 69 bp deletion variants of the Epstein-Barr virus LMP1 may arise by homologous recombination in nasopharyngeal carcinoma of Tunisian patients.
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ABSTRACT: Nasopharyngeal carcinoma (NPC) occurs with a striking geographic distribution, it is endemic in certain areas of Southeast Asia and North Africa. NPC is tightly linked to Epstein-Barr virus (EBV), however, only a small subset of EBV genes are expressed, among them the latent membrane protein 1 (LMP1). LMP1 is considered as the main EBV oncoprotein and its 30 bp deleted-variant has been reported to be more prevalent in biopsies of NPC. We have assessed the 30 bp deletion and the XhoI polymorphisms of the BNLF1 gene in 30 peripheral bloods of NPC patients and 62 nasopharyngeal biopsies, 42 being confirmed as undifferentiated nasopharyngeal carcinoma and 20 are normal nasopharyngeal epithelium cells. Our results show that 100% of individuals retained the XhoI restriction site. A rare NPC variant, having a 69 bp deletion in the C-terminus region of the BNLF1 gene, covering the 30 bp deletion, was found in two NPC biopsies. The deleted 30 and 69 bp deleted-variants are significantly (p = 0.006) more frequent in NPC (71.42%) than in control biopsies (52%). In peripheral blood of NPC patients, the deleted-variants (47%) are also lower than in tumor tissues (p = 0.0004), suggesting that the deletion could be associated with a risk of tumor genesis. Direct repeats, located at the extremities of the 30 and 69 bp deletions, should be involved in this process. We propose that other deletions could be found since another similar direct repeat is present at the vicinity of the former ones.Virus Research 02/2006; 115(1):24-30. · 2.94 Impact Factor -
Article: Identification of a novel frameshift mutation in the DFNB31/WHRN gene in a Tunisian consanguineous family with hereditary non-syndromic recessive hearing loss.
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ABSTRACT: Approximately 80% of hereditary hearing loss is non-syndromic. Non-syndromic deafness is the most genetically heterogeneous trait. The most common and severe form of hereditary hearing impairment is autosomal recessive non-syndromic hearing loss (ARNSHL), accounting for approximately 80% of cases of genetic deafness. To date, 22 genes implicated in ARNSHL have been identified. Recently a gene, DFNB31/WHRN, which encodes a putative PDZ scaffold protein called whirlin, was found to be responsible for the ARNSHL DFNB31. We found evidence for linkage to the DFNB31locus in a consanguineous Tunisian family segregating congenital profound ARNSHL. Mutation screening of DFNB31/WHRNrevealed four nonpathogenic sequence variants and a novel frameshift mutation [c.2423delG] + [c.2423delG] that changed the reading frame and induced a novel stop codon at amino acid 818 ([p.Gly808AspfsX11] + [p.Gly808AspfsX11]). To determine the contribution of the DFNB31locus in the childhood deafness, we performed linkage analysis in 62 unrelated informative families affected with ARNSHL. No linkage was found to this locus. From this study, we concluded that DFNB31/WHRN is most likely to be a rare cause of ARNSHL in the Tunisian population.Human Mutation 06/2005; 25(5):503. · 5.69 Impact Factor -
Article: A novel autosomal recessive non-syndromic deafness locus, DFNB66, maps to chromosome 6p21.2-22.3 in a large Tunisian consanguineous family.
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ABSTRACT: Hereditary non-syndromic deafness is extremely heterogeneous. Autosomal recessive forms account for approximately 80% of genetic cases. Autosomal recessive non-syndromic sensorineural deafness segregating in a large consanguineous Tunisian family was mapped to chromosome 6p21.2-22.3. A maximum lod score of 5.36 at theta=0 was obtained for the polymorphic microsatellite marker IR2/IR4. Haplotype analysis defined a 16.5-Mb critical region between microsatellite markers D6S1602 and D6S1665. The screening of 3 candidate genes, COL11A2, BAK1 and TMHS, did not reveal any disease causing mutation, suggesting that this is a novel deafness locus, which has been named DFNB66. A search in the Human Cochlear EST Library for ESTs located in this critical interval allowed us to identify several candidates. Further investigations on these candidates are needed in order to identify the deafness-causing gene in this Tunisian family.Human Heredity 02/2005; 60(3):123-8. · 1.79 Impact Factor -
Article: Mapping of a new autosomal recessive nonsyndromic hearing loss locus (DFNB32) to chromosome 1p13.3-22.1.
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ABSTRACT: Approximately 80% of the hereditary hearing loss is nonsyndromic. Isolated deafness is the most genetically heterogeneous trait. We have ascertained 10 individuals from a large consanguineous Tunisian family with congenital profound autosomal recessive deafness. All affected individuals are otherwise healthy. Genotype analysis excluded linkage to known recessive deafness loci in this family. Following a genome wide screening, a linkage was detected only with locus D1S206 on chromosome 1, thereby defining a novel deafness locus, DFNB32. In order to confirm linkage and for fine mapping the genetic interval, 12 individuals belonging to this family were added and 19 microsatellite markers were tested. A maximum two-point lodscore of 4.96 was obtained at a new polymorphic marker D1S21401. Haplotype analysis defined a 16 Mb critical region between D1S2868 and afmb014zb9. The interval of DFNB32 locus overlap with DFNA37 locus and the Marshall and Stickler syndromes locus. The entire coding region of COL11A1, responsible of the later syndromes, was screened and no mutation was observed. Towards the identification of the DFNB32 gene, a search on the Human Cochlear cDNA Library and EST Database was done. The genes corresponding to the ESTs found in the DFNB32 interval are being screened for deafness-causing mutations.European Journal of HumanGenetics 03/2003; 11(2):185-8. · 4.40 Impact Factor -
Article: Pendred syndrome: Phenotypic variability in two families carrying the same PDS missense mutation
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ABSTRACT: Pendred syndrome comprises congenital sensorineural hearing loss, thyroid goiter, and positive perchlorate discharge test. Recently, this autosomal recessive disorder was shown to be caused by mutations in the PDS gene, which encodes an anion transporter called pendrin. Molecular analysis of the PDS gene was performed in two consanguineous large families from Southern Tunisia comprising a total of 23 individuals affected with profound congenital deafness; the same missense mutation, L445W, was identified in all affected individuals. A widened vestibular aqueduct was found in all patients who underwent computed tomography (CT) scan exploration of the inner ear. In contrast, goiter was present in only 11 affected individuals, who interestingly had a normal result of the perchlorate discharge test whenever performed. The present results question the sensitivity of the perchlorate test for the diagnosis of Pendred syndrome and support the use of a molecular analysis of the PDS gene in the assessment of individuals with severe to profound congenital hearing loss associated with inner ear morphological anomaly even in the absence of a thyroid goiter. Am. J. Med. Genet. 90:38–44, 2000. © 2000 Wiley-Liss, Inc.American Journal of Medical Genetics 01/2000; 90(1):38 - 44. -
Article: Various 30 and 69bp deletion variants of the Epstein-Barr virus LMP1 may arise by homologous recombination in nasopharyngeal carcinoma of Tunisian patients
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ABSTRACT: Nasopharyngeal carcinoma (NPC) occurs with a striking geographic distribution, it is endemic in certain areas of Southeast Asia and North Africa. NPC is tightly linked to Epstein-Barr virus (EBV), however, only a small subset of EBV genes are expressed, among them the latent membrane protein 1 (LMP1). LMP1 is considered as the main EBV oncoprotein and its 30 bp deleted-variant has been reported to be more prevalent in biopsies of NPC. We have assessed the 30 bp deletion and the XhoI polymorphisms of the BNLF1 gene in 30 peripheral bloods of NPC patients and 62 nasopharyngeal biopsies, 42 being confirmed as undifferentiated nasopharyngeal carcinoma and 20 are normal nasopharyngeal epithelium cells. Our results show that 100% of individuals retained the XhoI restriction site. A rare NPC variant, having a 69 bp deletion in the C-terminus region of the BNLF1 gene, covering the 30 bp deletion, was found in two NPC biopsies. The deleted 30 and 69 bp deleted-variants are significantly (p = 0.006) more frequent in NPC (71.42%) than in control biopsies (52%). In peripheral blood of NPC patients, the deleted-variants (47%) are also lower than in tumor tissues (p = 0.0004), suggesting that the deletion could be associated with a risk of tumor genesis. Direct repeats, located at the extremities of the 30 and 69 bp deletions, should be involved in this process. We propose that other deletions could be found since another similar direct repeat is present at the vicinity of the former ones.Virus Research.
