Association of IVS6A GATT polymorphism of CFTR gene with cystic fibrosis: first study in CF and normal Tunisian population.

BACKGROUND: Cystic fibrosis (CF) is the most common autosomal recessive disease in Caucasians, caused by mutation in cystic fibrosis transmembrane conductance regulator (CFTR). The analysis of some extra and intragenic markers within or closely linked to CFTR gene is useful as a molecular method in clinical linkage analysis. Indeed, knowing that the molecular basis of CF is highly heterogeneous in our population is explained in the present study. In this work, we are interested for the first time to study the polymorphic marker IVS6a GATT in a CF Tunisian population. METHODS: Our study involved 80 CF Tunisian patients with a positive sweat test. A cohort of 90 healthy controls was also enrolled. The analysis of the variant IVS6a GATT was conducted by analysis of the fragments on automatic sequencer (ABI Prism 310). A statistical analysis was performed on Statistical Package for the Social Sciences (SPSS) version 20 software. RESULTS: The analysis of genotypic distribution of IVS6aGATT showed a significant difference between the control and CF groups suggesting the involvement of this marker in cystic fibrosis. Furthermore, we noted that the 6 GATT repetition in the homozygous state is more common in CF patients than in the control group (p <0.05). This while the 7GATT/7GATT genotype is more common among controls compared to CF patients (p = 0.002). Regarding the interest of this polymorphism on the clinical expression of cystic fibrosis, we have noted no significant association between 6/6 genotype with different clinical conditions in CF patients outside the CFTR mutation. While a significant association was found between respiratory involvement and mixed (respiratory and digestive) and the 6/6 genotype in patients with the mutation F508del homozygous (p <0.05). In addition, a significant association was also noted with gastrointestinal involvement for non F508del patients/F508del not (p = 0.014). Given that, phenotypic and genotypic heterogeneity of cystic fibrosis, several studies have sought to highlight the role of genetic markers linked to the CFTR gene in the expression and evolution of the disease. CONCLUSION: Our study on the implication of polymorphic marker IVS6a GATT is one of the first works carried out in the Tunisian population and confirms the usefulness of this marker in the clinical expression of cystic fibrosis.

A lower-cost protocol for sickle cell disease neonatal screening in Tunisia.

BACKGROUND AND OBJECTIVES: Sickle cell disease (SCD) is a group of hereditary chronic anemias that manifest essentially as painful crisis and susceptibility to infection. Neonatal screening is a preventive action that reduces the rates of mortality due to complications arising from infections by encouraging early prophylactic penicillin use and pneumococcal vaccination. The purpose of this pilot study was to set up a neonatal screening protocol at a lower cost than one that uses commercially available screening kits. DESIGN AND SETTING: Pilot study conducted over 1 year in two Tunis maternity hospitals. PATIENTS AND METHODS: Samples from 9148 newborns were collected using paper printed using a common office printer to collect blood spots from the newborns. A lab-prepared agarose gel for isoelectrofocusing (IEF) was used to test the dried blood samples from these newborns. RESULTS: The IEF on lab-prepared agarose gels was efficient since it was able to detect the main abnormal Hbs previously identified in the Tunisian population (HbS, HbC, HbO, and HbG). Furthermore, when data collected in this screening program were compared with the previously established national data, no statistically significant differences were found. After analysis, results were given back to the families of the patients, and the major Hb cases were directed to one of the hemoglobinopathies specialized centers, where at-risk couples benefited from genetic counselling and were informed about the possibility of prenatal diagnosis. CONCLUSION: This pilot experiment demonstrated the feasibility of SCD neonatal detection using a lower cost method as well as detection of other main structural Hb variants.