Common Service Units for Research in Genetics

Sousse, Tunisia

Common Service Units for Research in Genetics

Sousse, Tunisia
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Abdallah-Bouhjar I.B.,University of Sousse | Abdallah-Bouhjar I.B.,Common Service Units for Research in Genetics | Mougou-Zerelli S.,University of Sousse | Mougou-Zerelli S.,Common Service Units for Research in Genetics | And 10 more authors.
Journal of Pediatric Genetics | Year: 2013

We report on the cytogenetic and molecular investigations of constitutional de-novo ring chromosome 13s in three unrelated patients for better understanding and delineation of the phenotypic variability characterizing this genomic rearrangement. The patient’s karyotypes were as follows: 46, XY, r(13)(p11q34) dn for patients 1 and 2 and 46, XY, r(13)(p11q14) dn for patient 3, as a result of the deletion in the telomeric regions of chromosome 13. The patients were, therefore, monosomic for the segment 13q34→ 13qter; in addition, for patient 3, the deletion was larger, encompassing the segment 13q14 → 13qter. Fluorescence in situ hybridization confirmed these rearrangement and array CGH technique showed the loss of at least 2.9 Mb on the short arm and 4.7 Mb on the long arm of the chromosome 13 in patient 2. Ring chromosome 13 (r(13)) is associated with several phenotypic features like intellectual disability, marked short stature, brain and heart defects, microcephaly and genital malformations in males, including undescended testes and hypospadias. However, the hearing loss and speech delay that were found in our three patients have rarely been reported with ring chromosome 13. Although little is known about its etiology, there is interesting evidence for a genetic cause for the ring chromosome 13. We thus performed a genotype-phenotype correlation analysis to ascertain the contribution of ring chromosome 13 to the clinical features of our three cases. © 2013 - IOS Press and the authors.

Bouhjara I.B.A.,University of Sousse | Bouhjara I.B.A.,Common Service Units for Research in Genetics | Gmidene A.,University of Sousse | Mougou-Zrelli S.,University of Sousse | And 10 more authors.
Journal of Pediatric Genetics | Year: 2012

Mental retardation affects 1-3% of the population. To evaluate the implication of chromosomal abnormalities in the etiology of mental retardation, 1420 patients with non-syndromic mental retardation recruited at the department of cytogenetics of Farhat Hached hospital (Sousse, Tunisia) between January 2005 and December 2009, were analyzed using standard cytogenetic techniques. Age ranged between 3 and 18 years with a median of 8 years. Chromosomal abnormalities were detected in 7.8% of patients and an increased prevalence of chromosome anomalies was observed in patients when the mental retardation is associated with a severe degree of intellectual disability, facial dysmorphic features and/or congenital malformations or epilepsy. © 2012 - IOS Press and the authors.

Bouhjar I.B.A.,University of Sousse | Bouhjar I.B.A.,Common Service Units for Research in Genetics | Gmidene A.,University of Sousse | Gmidene A.,Common Service Units for Research in Genetics | And 9 more authors.
Journal of Pediatric Genetics | Year: 2012

In this study, we report two patients with the supernumerary marker chromosome (15)s. The first case is an 8.5-year-old girl with an inv dup (15) syndrome, mental retardation and dysmorphic features. The second case is a 13-year-old boy with a ring chromosome 15, who was referred to the Laboratory of Cytogenetic and Biology of Reproduction in Sousse, Tunisia for mental retardation, epilepsy, speech delay, hypotonia and other mild dysmorphic features. R banding showed the presence of a marker chromosome in both cases. Molecular cytogenetic investigation using fluorescence in situ hybridization method allowed us to characterize the markers including the Prader-Willi syndrome locus that contains the small nuclear ribonucleoprotein polypeptide N (SNRPN) gene. Tetrasomy and trisomy for the 15q11-q13 chromosomal region were found in the first and the second patient, respectively. This observation reinforces the hypothesis that additional copies of proximal chromosome 15q11 segment may be causally related to mental retardation and dysmorphic features. © 2012 - IOS Press and the authors.

Bouraoui S.,University of Sousse | Mougou S.,University of Sousse | Drira A.,University of Sousse | Tabka F.,University of Sousse | And 5 more authors.
International Journal of Occupational Medicine and Environmental Health | Year: 2013

Objectives: The aim of this study is to assess chromosomal damage in Tunisian hospital workers occupationally exposed to low levels of ionizing radiation (IR). Materials and Methods: The cytokinesis-block micronucleus (CBMN) assay in the peripheral lymphocytes of 67 exposed workers compared to 43 controls matched for gender, age and smoking habits was used. The clastogenic/aneugenic effect of IR was evaluated using the CBMN assay in combination with fluorescence in situ hybridization with human pan-centromeric DNA in all the exposed subjects and controls. Results: The study showed a significant increase of the micronucleus (MN) frequency in the lymphocytes of the exposed workers compared to the control group (13.63±4.9‰ vs. 6.52±4.21‰, p < 0.05). The centromere analysis performed in our study showed that MNs in hospital staff were predominantly centromere negative (72%) and the mean negative labeled micronucleus (C-MN) frequency was significantly higher in the exposed subjects than in the controls (9.04±4.57‰ vs. 1.17±0.77‰). The multivariate regression analysis, taking into account all confounding factors, showed that only the time of exposure to IR had a significant effect on the level of MNs and C-MN. Conclusion: The present study shows that chromosomal damage leading to the formation of micronucleated lymphocytes is more frequent in the hospital workers exposed to IR than in the controls, despite the low levels of exposure. The results of the study confirm the well-known clastogenic properties of ionizing radiation. In regards to health monitoring, detection of early genotoxic effects may allow for the adoption of preventive biological control measures, such as hygienic improvements in the workplace or reduction of hours of occupational exposure. © 2013 Versita Warsaw and Springer-Verlag Wien.

Abdallah Bouhjar I.B.,University of Sousse | Hannachi H.,University of Sousse | Mougou Zerelli S.,University of Sousse | Labalme A.,Hospices Civils de Lyon | And 8 more authors.
American Journal of Medical Genetics, Part A | Year: 2011

Partial trisomy 9p is one of the most common detected autosomal structural anomalies, so the phenotype-genotype correlation of this rearrangement has been well described. Despite variation in size of the 9p duplications, trisomy 9p syndrome is characterized by typical dysmorphic features and a variable but constant psychomotor and mental retardation. Previously reported phenotype genotype correlation studies proposed that the critical region for phenotype is located in 9p22. We report here on a new patient with partial trisomy 9p13.3→9pter in an 8-year-old boy with typical trisomy 9p dysmorphic features but a normal mental development. Cytogenetics investigations showed that our patient karyotype was 47,XY,+ der(22)t(9;22)(p13.q11) inherited by a 3:1 disjunction of a maternal reciprocal translocation t(9;22)(p13.q11). FISH and array CGH analysis were used to better characterize duplicated chromosomal regions and showed a large duplication of chromosome 9p13.3→9pter associated to microduplication in 22q11.1. The size of the duplications in chromosomes 9p and 22q were estimated about 33.9 and 2.67Mb, respectively. The comparison between this case and those reported in the literature allows us to support that all syndromes show variability and that not all partial trisomies 9p are associated with intellectual disability. © 2011 Wiley-Liss, Inc.

Bouraoui S.,University of Sousse | Mougou S.,University of Sousse | Brahem A.,University of Sousse | Tabka F.,University of Sousse | And 6 more authors.
Archives of Environmental Contamination and Toxicology | Year: 2013

A genotoxic effect of formaldehyde (FA), particularly micronucleus (MN) induction, has been shown in several previous studies. The aim of the present study was to assess the frequency of micronuclei and to identify the type of chromosomal damage in Tunisian staff members working in the Pathologic Anatomy Laboratory of Farhat Hached hospital (Sousse, Tunisia) who were exposed to FA. Assessment of chromosomal damage was performed in peripheral lymphocytes of 31 FA-exposed employees compared with 31 control employees working in the administrative department of the same hospital. The clastogenic/aneugenic effect of FA was evaluated using the standard MN assay in combination with fluorescence in situ hybridization (FISH) using pan-centromeric probes. The mean level of exposure to FA was 3.4 ppm. The results showed a significant increase of MN frequency in lymphocytes of exposed workers compared with the control group (25.35 ± 6.28 ‰ vs. 7.08 ± 4.62 ‰, p < 0.05). As assessed by FISH, the frequency of centromeric micronuclei (C+MN) was greater in exposed subjects than in controls (18.38 ± 5.94 ‰ vs. 5.03 ± 3.64 ‰). Among the C+MN, the frequency of MN containing one centromere (C1+MN) was significantly greater in pathologists and anatomists than in controls (15.35 ± 6.0 ‰ vs. 3.33 ± 2.74 ‰, p < 0.05). The results showed an effect of sex and time of FA exposure with significantly increased frequencies of all end points measuring aneuploidy (C+MN, C1+MN, and Cx+MN [more then one MN]). The increased frequency of C1+MN observed in the exposed group may suggest a slight aneugenic effect of FA exposure. © 2012 Springer Science+Business Media New York.

Ben Abdallah I.,University of Sousse | Hannachi H.,University of Sousse | Soyah N.,University of Sousse | Saad A.,University of Sousse | And 3 more authors.
Pediatric Neurology | Year: 2011

Chromosomal imbalances comprise a major cause of mental retardation, particularly in association with congenital malformations and dysmorphic features. Chromosomal analysis using banded karyotyping is limited by the low resolution of this technique, and cryptic chromosomal rearrangements cannot be detected. We describe a 6-year-old girl with mental retardation, mild growth, congenital malformation, and facial anomalies. Chromosomal analysis with karyotyping produced normal results. Because the phenotype suggested chromosomal abnormality, microarray comparative genomic hybridization was used to search for a possible cryptic anomaly. A subtelomeric chromosomal imbalance, consisting of partial trisomy 2q35 and partial monosomy 3p26, was detected and confirmed using fluorescence in situ hybridization. This rearrangement was inherited from an equilibrated maternal t(2;3) reciprocal translocation. Comparative genomic hybridization array in similar situations is useful in detecting cryptic chromosomal rearrangements, identifying genes contained in deleted or duplicated regions, establishing a precise phenotype-genotype correlation, and offering unambiguous genetic counseling. © 2011 by Elsevier Inc. All rights reserved.

Ben-Abdallah-Bouhjar I.,University of Sousse | Ben-Abdallah-Bouhjar I.,Common Service Units for Research in Genetics | Hannachi H.,University of Sousse | Hannachi H.,Common Service Units for Research in Genetics | And 11 more authors.
European Journal of Medical Genetics | Year: 2012

Duplications of the long arm of the X chromosome are rare. The infantile phenotype shares some resemblance with the Prader-Willi syndrome, presenting severe psychomotor retardation, facial dysmorphic features with a broad face, a small mouth and a thin pointed nose, hypotonia, urogenital malformation and proneness to infections. We report a boy with an additional Xq27-qter chromosome segment translocated onto the short arm of chromosome 3. The karyotype was 46,XY,der(3)t(X;3)(q27.3; p26.3)mat. This cryptic unbalanced X-autosome translocation resulted in Xq27-qter functional disomy and a deletion 3p26.3. A detailed analysis of the constitutional chromosomal changes in the patient was performed using array-CGH, FISH and PCR. The aim was to characterize the size and the location of the duplication Xq27-qter (8.18 Mb) and of the deletion 3p26.3 (1.05 Mb), to establish phenotype-genotype correlations and to offer genetic counselling. © 2012 Elsevier Masson SAS.

Bouraoui S.,University of Sousse | Brahem A.,University of Sousse | Tabka F.,University of Sousse | Mrizek N.,University of Sousse | And 3 more authors.
Environmental Toxicology and Pharmacology | Year: 2011

Anti-neoplastic agents are widely used in the treatment of cancer and some non-neoplastic diseases. These drugs have been proved to be mutagens, carcinogens and teratogens.To check the eventual effects of anti-cancer drugs on occupationally exposed Tunisian nurses, we used chromosomal aberration assay and micronucleus assay. Both parameters have been used to evaluate cellular DNA damage in the biological monitoring of occupationally exposed workers and each assay has its own aim .We used the proliferation rate index to evaluate the cytotoxic effect of antineoplastic drugs in exposed nurses.The frequency of binucleated micronucleated cells was significantly higher in nurses handling cytostatic drugs than in control.We detected also a significant increase of structural chromosomal aberrations.Control subjects generally had significantly higher values of proliferation rate index compared to expose ones.Our results confirm the genotoxic and the cytotoxic effects of antineoplastic drugs in blood lymphocytes circulation. This study points to the necessity to work under more safe and controlled conditions during the preparation and the administration of anti-cancer drugs. © 2010 Elsevier B.V.

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