| 1. |
- Ben Said, Mariem, et al.
(author)
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Posterior microphthalmia and nanophthalmia in Tunisia caused by a founder c.1059_1066insC mutation of the PRSS56 gene
- 2013
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In: Gene. - : Elsevier. - 0378-1119 .- 1879-0038. ; 528:2, s. 288-294
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Journal article (peer-reviewed)abstract
- Congenital microphthalmia (CMIC) is a common developmental ocular disorder characterized by a small, and sometimes malformed, eye. Posterior microphthalmia (PM) and nanophthalmia are two rare subtypes of isolated CMIC characterized by extreme hyperopia due to short axial length and elevated lens/eye volume ratio. While nanophthalmia is associated with a reduced size in both anterior and posterior segments, PM involves a normal-size anterior chamber but a small posterior segment. less thanbrgreater than less thanbrgreater thanSeveral genes encoding transcription and non-transcription regulators have been identified in different forms of CMIC. MFRP gene mutations have, for instance, been associated with nanophthalmia, and mutations in the recently identified PRSS56 gene have been linked to PM. So far, these two forms of CMIC have been associated with 9 mutations in PRSS56. Of particular interest, a c.1059_1066insC mutation has recently been reported in four Tunisian families with isolated PM and one Tunisian family with nanophthalmia. Here, we performed a genome-wide scan using a high density single nucleotide polymorphism (SNP) array 50 K in a large consanguineous Tunisian family (PM7) affected with PM and identified the same causative disease mutation. A total of 24 polymorphic markers spanning the PRSS56 gene in 6 families originating from different regions of Tunisia were analyzed to investigate the origin of the c.1059_1066insC mutation and to determine whether it arose in a common ancestor. A highly significant disease-associated haplotype, spanning across the 146 kb of the 2q37.1 chromosome, was conserved in those families, suggesting that c.1059_1066insC arose from a common founder. The age of the mutation in this haplotype was estimated to be around 1850 years. The identification of such founder effects may greatly simplify diagnostic genetic screening and lead to better prognostic counseling.
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| 2. |
- Chibani, Zohra, et al.
(author)
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Autosomal recessive congenital hereditary corneal dystrophy associated with a novel SLC4A11 mutation in two consanguineous Tunisian families
- 2022
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In: British Journal of Ophthalmology. - : BMJ PUBLISHING GROUP. - 0007-1161 .- 1468-2079. ; 106:2, s. 281-287
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Journal article (peer-reviewed)abstract
- Background Autosomal recessive congenital hereditary corneal dystrophy (CHED) is a rare isolated developmental anomaly of the eye characterised by diffuse bilateral corneal clouding that may lead to visual impairment requiring corneal transplantation. CHED is known to be caused by mutations in the solute carrier family 4 member 11 (SLC4A11) gene which encodes a membrane transporter protein (sodium bicarbonate transporter-like solute carrier family 4 member 11). Methods To identify SLC4A11 gene mutations associated with CHED (OMIM: #217700), genomic DNA was extracted from whole blood and sequenced for all exons and intron-exon boundaries in two large Tunisian families. Results A novel deletion SLC4A11 mutation (p. Leu479del; c.1434_1436del) is responsible for CHED in both analysed families. This non-frameshift mutation was found in a homozygous state in affected members and heterozygous in non-affected members. In silico analysis largely support the pathogenicity of this alteration that may leads to stromal oedema by disrupting the osmolarity balance. Being localised to a region of alpha-helical secondary structure, Leu479 deletion may induce protein-compromising structural rearrangements. Conclusion To the best of our knowledge, this is the first clinical and genetic study exploring CHED in Tunisia. The present work also expands the list of pathogenic genotypes in SLC4A11 gene and its associated clinical diagnosis giving more insights into genotype-phenotype correlations.
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| 3. |
- Chibani, Zohra, et al.
(author)
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Novel BEST1 gene mutations associated with two different forms of macular dystrophy in Tunisian families
- 2019
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In: Clinical and Experimental Ophthalmology. - : Wiley-Blackwell Publishing Inc.. - 1442-6404 .- 1442-9071. ; 47:8, s. 1063-1073
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Journal article (peer-reviewed)abstract
- BackgroundEpidemiological studies of hereditary eye diseases allowed us to identify two Tunisian families suffering from macular dystrophies: Best vitelliform macular dystrophy (BVMD) and autosomal recessive bestrophinopathy (ARB). The purpose of the current study was to investigate the clinical characteristics and the underlying genetics of these two forms of macular dystrophy.MethodsComplete ophthalmic examination was performed including optical coherence tomography, electroretinography, electrooculography and autofluoresence imaging in all patients. Genomic DNA was extracted from peripheral blood collected from patients and family members.ResultsSanger sequencing of all exons of the BEST1 gene in both families identified two new mutations: a missense mutation c.C91A [p.L31 M] at the N‐terminal transmembrane domain within the ARB family and a nonsense mutation C1550G (p.S517X) in the C‐terminal domain segregating in the BVMD family.ConclusionsSeveral mutations of the BEST1 gene have been reported which are responsible for numerous ocular pathologies. To the best of our knowledge, it is the first time we report mutations in this gene in Tunisian families presenting different forms of macular dystrophy. Our report also expands the list of pathogenic BEST1 genotypes and the associated clinical diagnosis.
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| 4. |
- Fagerås Böttcher, Malin, et al.
(author)
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A TLR4 polymorphism is associated with asthma and reduced lipopolysaccharide-induced interleukin-12(p70) responses in Swedish children
- 2004
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In: Journal of Allergy and Clinical Immunology. - : Elsevier BV. - 0091-6749 .- 1097-6825. ; 114:3, s. 561-567
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Journal article (peer-reviewed)abstract
- Background Bacterial signals play an important role in the maturation of the immune system. Polymorphisms in genes coding for receptors to bacterial components can alter the immune responsiveness of the host to microbial agents and may indicate the development of aberrant immune responses that are associated with immune-mediated diseases such as atopic diseases. Objective The study's objective was to investigate the relationship between TLR4 and CD14 gene polymorphisms, the LPS responsiveness of PBMCs, and the presence of asthma and allergic rhinoconjunctivitis in children. Methods The TLR4 (Asp299Gly) and CD14/−159 polymorphisms were determined in 115 Swedish children aged 8 and 14 years. LPS-induced IL-12(p70), IL-10, and IFN-γ responses of PBMCs from 69 of the children were analyzed by means of ELISA. The levels of soluble CD14 in serum samples were analyzed by means of ELISA, and the total IgE levels were analyzed by means of UniCAP Total IgE (Pharmacia Diagnostics, Uppsala, Sweden). Results Decreased LPS-induced IL-12(p70) and IL-10 responses were associated with the TLR4 (Asp299Gly) polymorphism and independently with asthma, especially atopic asthma. The TLR4 (Asp299Gly) polymorphism was associated with a 4-fold higher prevalence of asthma in school-aged children (adjusted odds ratio 4.5, 95% CI 1.1-17.4) but not to allergic rhinoconjunctivitis. Conclusion A TLR4 polymorphism modifies innate immune responses in children and may be an important determinant for the development of asthma. This may influence the outcome of intervention studies that use microbial stimuli as immune modulators.
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| 5. |
- Grahn, Niclas, et al.
(author)
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Molecular identification of Helicobacter DNA present in human colorectal adenocarcinomas by 16S rDNA PCR amplification and pyrosequencing analysis
- 2005
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In: Journal of Medical Microbiology. - : Microbiology Society. - 0022-2615 .- 1473-5644. ; 54:11, s. 1031-1035
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Journal article (peer-reviewed)abstract
- Seroepidemiological studies have indicated that Helicobacter pylori infection might be a possible risk factor for colorectal adenocarcinoma (CRC) development. However, limited information is available as to whether or not Helicobacter species are present in CRC tissues. In this study the presence of Helicobacter DNA in 77 CRC biopsies was investigated by means of a Helicobacter species-specific 16S rDNA PCR assay and real-time DNA pyrosequencing of the 16S rDNA variable V3 region. Pyrosequencing revealed the presence of Helicobacter DNA sequences in 21 of 77 biopsy specimens (27%). 16S rDNA sequences corresponding to H. pylori 26695 and H. pylori J99 were most commonly found. Intriguingly, one sequence belonged to Helicobacter mustelae, previously identified in ferrets. No significant correlations were found in the prevalence of Helicobacter DNA between colon and rectum tumour biopsies (P = 0.815), nor between Dukes' classes A/B and C/D (P = 0.262). 16S rDNA PCR amplification combined with pyrosequencing analysis of 16S rDNA variable V3 regions provides a powerful molecular tool to identify Helicobacter species in human biopsy specimens. © 2005 SGM.
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| 6. |
- Hmani-Aifa, Mounira, et al.
(author)
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A genome-wide linkage scan in Tunisian families identifies a novel locus for non-syndromic posterior microphthalmia to chromosome 2q37.1
- 2009
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In: HUMAN GENETICS. - : Springer Science and Business Media LLC. - 0340-6717 .- 1432-1203. ; 126:4, s. 575-587
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Journal article (peer-reviewed)abstract
- Posterior microphthalmia (PM) is a relatively rare autosomal recessive condition with normal anterior segment and small posterior segment resulting in high hyperopia and retinal folding. It is an uncommon subtype of microphthalmia that has been mostly reported to coexist with several other ophthalmic conditions and to occur in sporadic cases. The membrane-type frizzled-related protein (MFRP) is the only gene so far reported implicated in autosomal recessive, non-syndromic and syndromic forms of PM. Here, we performed a clinical and genetic analysis using six consanguineous families ascertained from different regions of Tunisia and affected with non-syndromic PM that segregates as an autosomal recessive trait. To identify the disease-causing defect in these families, we first analysed MFRP gene, then some candidate genes (CHX10, OPA1, MITF, SOX2, CRYBB1-3 and CRYBA4) and loci (MCOP1, NNO1 and NNO2) previously implicated in different forms of microphthalmia. After exclusion of these genes and loci, we performed a genome-wide scan using a high density single nucleotide polymorphism (SNP) array 50 K in a large consanguineous pedigree. SNP genotyping revealed eight homozygous candidate regions on chromosomes 1, 2, 3, 6, 15, 17 and 21. Linkage analysis with additional microsatellite markers only retained the 2q37.1 region with a maximum LOD score of 8.85 obtained for D2S2344 at theta = 0.00. Further investigations are compatible for linkage of four more families to this region with a refined critical interval of 2.35 Mb. The screening of five candidate genes SAG, PDE6D, CHRND, CHRNG and IRK13 did not reveal any disease-causing mutation.
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| 7. |
- Hmani-Aifa, Mounira, et al.
(author)
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Identification of two new mutations in the GPR98 and the PDE6B genes segregating in a Tunisian family
- 2009
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In: EUROPEAN JOURNAL OF HUMAN GENETICS. - : Springer Science and Business Media LLC. - 1018-4813 .- 1476-5438. ; 17:4, s. 474-482
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Journal article (peer-reviewed)abstract
- Autosomal recessive retinitis pigmentosa (ARRP) is a genetically heterogeneous disorder. ARRP could be associated with extraocular manifestations that define specific syndromes such as Usher syndrome (USH) characterized by retinal degeneration and congenital hearing loss (HL). The USH type II (USH2) associates RP and mild-to-moderate HL with preserved vestibular function. At least three genes USH2A, the very large G-protein-coupled receptor, GPR98, and DFNB31 are responsible for USH2 syndrome. Here, we report on the segregation of non-syndromic ARRP and USH2 syndrome in a consanguineous Tunisian family, which was previously used to define USH2B locus. With regard to the co-occurrence of these two different pathologies, clinical and genetic reanalysis of the extended family showed (i) phenotypic heterogeneity within USH2 patients and (ii) excluded linkage to USH2B locus. Indeed, linkage analysis disclosed the cosegregation of the USH2 phenotype with the USH2C locus markers, D5S428 and D5S618, whereas the ARRP perfectly segregates with PDE6B flanking markers D4S3360 and D4S2930. Molecular analysis revealed two new missense mutations, p. Y6044C and p. W807R, occurring in GPR98 and PDE6B genes, respectively. In conclusion, our results show that the USH2B locus at chromosome 3p23-24.2 does not exist, and we therefore withdraw this locus designation. The combination of molecular findings for GPR98 and PDE6B genes enable us to explain the phenotypic heterogeneity and particularly the severe ocular affection first observed in one USH2 patient. This report presents an illustration of how consanguinity could increase familial clustering of multiple hereditary diseases within the same family.
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| 8. |
- Saidas Nair, K, et al.
(author)
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Alteration of the serine protease PRSS56 causes angle-closure glaucoma in mice and posterior microphthalmia in humans and mice
- 2011
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In: NATURE GENETICS. - : Nature Publishing Group. - 1061-4036 .- 1546-1718. ; 43:6, s. 579-U118
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Journal article (peer-reviewed)abstract
- Angle-closure glaucoma (ACG) is a subset of glaucoma affecting 16 million people(1-3). Although 4 million people are bilaterally blind from ACG(4,5), the causative molecular mechanisms of ACG remain to be defined. High intraocular pressure induces glaucoma in ACG. High intraocular pressure traditionally was suggested to result from the iris blocking or closing the angle of the eye, thereby limiting aqueous humor drainage. Eyes from individuals with ACG often have a modestly decreased axial length, shallow anterior chamber and relatively large lens, features that predispose to angle closure(6). Here we show that genetic alteration of a previously unidentified serine protease (PRSS56) alters axial length and causes a mouse phenotype resembling ACG. Mutations affecting this protease also cause a severe decrease of axial length in individuals with posterior microphthalmia. Together, these data suggest that alterations of this serine protease may contribute to a spectrum of human ocular conditions including reduced ocular size and ACG.
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