Sister chromatid exchange (SCE) and high-frequency cells (HFC) in peripheral blood lymphocytes of healthy Tunisian smokers.

Cigarette smoking is a major public health problem in Tunisia as it concerns up to 30-35% of the adult population, raising important national issues on tobacco-related disease. The aim of this study was to establish whether cigarette smoking increases sister chromatid exchange (SCE) in peripheral blood lymphocytes of smokers (n=14) compared with non-smokers (n=15) in Sfax, Tunisia. The smokers were subdivided in two subgroups according to the duration of the smoking habit: heavy smokers (>10 years) and light smokers (≤10 years). After signing a consent form, volunteers provided a blood sample (5ml) to establish cell cultures during 72h. For SCE analysis, 30 second-division metaphases were examined from each subject. We determined the frequency of SCE, the percentage of high-frequency cells (HFC) and that of the high-frequency cell individual (HFI). The results show a significantly higher SCE frequency in smokers (8.65±1.43) than in non-smokers (7.16±1.3; p<0.01). A significant difference in SCE frequency was also shown when comparing the two subgroups of smokers (p<0.05). Interestingly, no significant difference was found when comparing the light smokers with non-smokers (7.82±1 vs 7.16±1.3, respectively, p>0.05). The percentages of HFC and HFI were significantly higher in smokers (11.2±7.8% and 78.6%, respectively) than in non-smokers (4±2.2% and 20%, respectively, p<0.01). Our study indicates that the genotoxic effects in lymphocytes from healthy Tunisian smokers are most likely caused by cigarette-smoke constituents. This effect was mainly observed in smokers who had been smoking during more than 10 years. These results provide scientific evidence to urge the prevention of tobacco consumption.

Screening of the eight BBS genes in Tunisian families: no evidence of triallelism.

PURPOSE: To study Bardet-Biedl syndrome (BBS) in the Tunisian population and determine the presence of triallelism in the eight identified BBS genes. METHODS: DNA samples were collected from 19 consanguineous Tunisian families with BBS. Genome-wide scans were performed with microsatellite markers in 12 families, and two-point linkage analyses were performed. Direct sequencing was used to screen patients with BBS for mutations in all eight identified BBS genes. RESULTS: Mutations in the BBS genes were identified in nine families. In addition, a large consanguineous family (57004) showed linkage to the BBS7 locus, although no mutation was identified. Five novel mutations were present in the nine families: one in BBS2 (c.565C>T, p.ArgR189Stop), one in BBS5 (c.123delA, p.Gly42GlufsX11), one in BBS7 (g.47247455_47267458del20004insATA, p.Met284LysfsX7), and two in BBS8 (c.459+1G>A, p.Pro101LeufsX12 and c.355_356insGGTGGAAGGCCAGGCA, p.Thr124ArgfsX43). CONCLUSIONS: All families in which mutations were identified show changes in both copies of the mutant gene, and inheritance patterns in all families are consistent with autosomal recessive inheritance excluding any evidence of triallelism in the BBS genes in Tunisia.