Single nucleotide polymorphisms of SCN5A and SCN10A genes increase the risk of ventricular arrhythmias during myocardial infarction.

BACKGROUND: Coronary artery disease (CAD) and its ultimate consequence - myocardial infarction (MI) - are major causes of sudden cardiac death (SCD). Previous studies have demonstrated the role of genetic polymorphisms in the risk of SCD and ventricular arrhythmia (VA) during MI. OBJECTIVES: To investigate the association between single nucleotide polymorphisms (SNPs) of genes implicated in congenital cardiac arrhythmias and the risk of developing VA in the context of MI. MATERIAL AND METHODS: We performed a case-control study in which we genotyped 4 SNPs (rs11708996, rs10428132, rs9388451, and rs2200733) in 469 subjects using amplification refractory mutation system (ARMS) and a polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). These SNPs are located in the SCN5A, SCN10A, HEY2, and PITX2 genes, respectively. We first compared 70 patients who had developed VA in the context of MI with 141 healthy controls; next, we compared VA patients with 258 MI patients who did not develop VA during a 1-year follow up. The statistical analyses were adjusted for sex and age. RESULTS: Compared to the controls, 2 polymorphisms were significantly associated with the development of VA during MI, located in SCN5A rs11708996 (p = 0.001) and SCN10A rs10428132 (p = 0.001). Similar results were found when comparing VA cases with patients without VA. No associations of HEY2 and PITX2 polymorphisms were observed. CONCLUSIONS: Our results suggest that the rs11708996 and rs10428132 polymorphisms of the SCN5A and SCN10A genes may contribute to an elevated risk of developing VA in the context of MI. The associated alleles or genotypes may be used to predict the risk, and thus prevent eventual SCD.

Role of SCN5A coding and non-coding sequences in Brugada syndrome onset: What's behind the scenes?

BACKGROUND: Brugada syndrome (BrS) is a rare inherited cardiac arrhythmia associated with a high risk of sudden cardiac death (SCD) due to ventricular fibrillation (VF). BrS is characterized by coved-type ST-segment elevation in the right precordial leads (V1-V3). Mutations in SCN5A gene coding for the α-subunit of the NaV1.5 cardiac sodium channel are identified in 15-30% of BrS cases. Genetic testing of BrS patients generally involves sequencing of the protein-coding portions and flanking intronic regions of SCN5A. This excludes the 5'UTR and 3'UTR from the routine genetic testing. METHODS: We here screened the coding sequence, the flanking intronic regions as well as the 5' and 3'UTR regions of SCN5A gene and further five candidate genes (GPD1L, SCN1B, KCNE3, SCN4B, and MOG1) in a Tunisian family diagnosed with BrS. RESULTS: A new SCN5A-Q1000K mutation was identified along with two common polymorphisms (H558R and D1819). Multiple genetic variants were identified on the SCN5A 3'UTR, one of which is predicted to create additional microRNA binding site for miR-1270. Additionally, we identified the hsa-miR-219a-rs107822. No relevant coding sequence variant was identified in the remaining studied candidate genes. CONCLUSIONS: The absence of genotype-phenotype concordance within all the identified genetic variants in this family gives extra evidences about the complexity of the disease and suggests that the occurrence and prognosis of BrS is most likely controlled by a combination of multiple genetic factors, rather than a single variant. Most SCN5A variants were localized in non-coding regions hypothesizing an impact on the miRNA-target complementarities.

The Role of Recent Admixture in Forming the Contemporary West Eurasian Genomic Landscape.

Over the past few years, studies of DNA isolated from human fossils and archaeological remains have generated considerable novel insight into the history of our species. Several landmark papers have described the genomes of ancient humans across West Eurasia, demonstrating the presence of large-scale, dynamic population movements over the last 10,000 years, such that ancestry across present-day populations is likely to be a mixture of several ancient groups [1-7]. While these efforts are bringing the details of West Eurasian prehistory into increasing focus, studies aimed at understanding the processes behind the generation of the current West Eurasian genetic landscape have been limited by the number of populations sampled or have been either too regional or global in their outlook [8-11]. Here, using recently described haplotype-based techniques [11], we present the results of a systematic survey of recent admixture history across Western Eurasia and show that admixture is a universal property across almost all groups. Admixture in all regions except North Western Europe involved the influx of genetic material from outside of West Eurasia, which we date to specific time periods. Within Northern, Western, and Central Europe, admixture tended to occur between local groups during the period 300 to 1200 CE. Comparisons of the genetic profiles of West Eurasians before and after admixture show that population movements within the last 1,500 years are likely to have maintained differentiation among groups. Our analysis provides a timeline of the gene flow events that have generated the contemporary genetic landscape of West Eurasia.

Absence of family history and phenotype-genotype correlation in pediatric Brugada syndrome: more burden to bear in clinical and genetic diagnosis.

Brugada syndrome (BrS) is an autosomal-dominant genetic cardiac disorder caused in 18-30 % of the cases by SCN5A gene mutations and manifested by an atypical right bundle block pattern with ST segment elevation and T wave inversion in the right precordial leads. The syndrome is usually detected after puberty. The identification of BrS in pediatric patients is thus a rare occurrence, and most of the reported cases are unmasked after febrile episodes. Usually, having a family history of sudden death represents the first reason to perform an ECG in febrile children. However, this practice makes the sporadic cases of cardiac disease and specially the asymptomatic ones excluded from this diagnosis. Here, we report a sporadic case of a 2-month-old male patient presented with vaccination-related fever and ventricular tachycardia associated with short breathing, palpitation and cold sweating. ECG changes were consistent with type 1 BrS. SCN5A gene analysis of the proband and his family revealed a set of mutations and polymorphisms differentially distributed among family members, however, without any clear genotype-phenotype correlation. Based on our findings, we think that genetic testing should be pursued as a routine practice in symptomatic and asymptomatic pediatric cases of BrS, with or without family history of sudden cardiac death. Similarly, our study suggests that pediatrician should be encouraged to perform an ECG profiling in suspicious febrile children and quickly manage fever since it is the most important factor unmasking BrS in children.

Regulation of SCN5A by microRNAs: miR-219 modulates SCN5A transcript expression and the effects of flecainide intoxication in mice.

BACKGROUND: The human cardiac action potential in atrial and ventricular cells is initiated by a fast-activating, fast-inactivating sodium current generated by the SCN5A/Nav1.5 channel in association with its ß1/SCN1B subunit. The role of Nav1.5 in the etiology of many cardiac diseases strongly suggests that proper regulation of cell biology and function of the channel is critical for normal cardiac function. Hence, numerous recent studies have focused on the regulatory mechanisms of Nav1.5 biosynthetic and degradation processes as well as its subcellular localization. OBJECTIVE: The purpose of this study was to investigate the role of microRNAs in the Scn5a/Nav1.5 posttranscriptional regulation. METHODS: Quantitative polymerase chain reaction, immunohistochemical and electrophysiological measurements of distinct microRNA gain-of-function experiments in cardiomyocytes for the assessment of Scn5a expression. RESULTS: Functional studies of HL-1 cardiomyocytes and luciferase assays in fibroblasts demonstrate that Scn5a is directly (miR-98, miR-106, miR-200, and miR-219) and indirectly (miR-125 and miR-153) regulated by multiple microRNAs displaying distinct time-dependent profiles. Cotransfection experiments demonstrated that miR-219 and miR-200 have independent opposite effects on Scn5a expression modulation. Of all the microRNAs studied, only miR-219 increases Scn5a expression levels, leading to altered contraction rhythm of HL-1 cardiomyocytes. Electrophysiological analyses in HL-1 cells revealed that miR-219 increases the sodium current. In vivo administration of miR-219 does not alter normal cardiac rhythm, but abolishes some of the effects of flecainide intoxication in mice, particularly QRS prolongation. CONCLUSION: This study demonstrates the involvement of multiple microRNAs in the regulation of Scn5a. Particularly, miR-219 increases Scn5a/Nav1.5 transcript and protein expression. Our data suggest that microRNAs, such as miR-219, constitute a promising therapeutical tool to treat sodium cardiac arrhythmias.

Novel ATP6V0A4 mutation described in a Tunisian patient with distal renal tubular acidosis.

UNLABELLED: Few data regarding molecular diagnosis of primary distal renal tubular acidosis (DRTA) in Tunisian population are available. CASE REPORT: 25-day-old male patient from consanguineous parents of Tunisian origin diagnosed with DRTA and without hearing impairment observed later in life. ATP6V0A4 gene sequencing demonstrated a novel homozygous G deletion in exon 13 (c.1221delG, p.Met408CysfsX10), leading to a premature stop codon. CONCLUSION: A novel ATP6V0A4 gene mutation confirmed autosomal recessive DRTA with normal hearing in the patient. Molecular analysis may help to rapidly diagnose autosomal recessive DRTA in Tunisian population.

Molecular diagnosis of distal renal tubular acidosis in Tunisian patients: proposed algorithm for Northern Africa populations for the ATP6V1B1, ATP6V0A4 and SCL4A1 genes.

BACKGROUND: Primary distal renal tubular acidosis (dRTA) caused by mutations in the genes that codify for the H + -ATPase pump subunits is a heterogeneous disease with a poor phenotype-genotype correlation. Up to now, large cohorts of dRTA Tunisian patients have not been analyzed, and molecular defects may differ from those described in other ethnicities. We aim to identify molecular defects present in the ATP6V1B1, ATP6V0A4 and SLC4A1 genes in a Tunisian cohort, according to the following algorithm: first, ATP6V1B1 gene analysis in dRTA patients with sensorineural hearing loss (SNHL) or unknown hearing status. Afterwards, ATP6V0A4 gene study in dRTA patients with normal hearing, and in those without any structural mutation in the ATP6V1B1 gene despite presenting SNHL. Finally, analysis of the SLC4A1 gene in those patients with a negative result for the previous studies. METHODS: 25 children (19 boys) with dRTA from 20 families of Tunisian origin were studied. DNAs were extracted by the standard phenol/chloroform method. Molecular analysis was performed by PCR amplification and direct sequencing. RESULTS: In the index cases, ATP6V1B1 gene screening resulted in a mutation detection rate of 81.25%, which increased up to 95% after ATP6V0A4 gene analysis. Three ATP6V1B1 mutations were observed: one frameshift mutation (c.1155dupC; p.Ile386fs), in exon 12; a G to C single nucleotide substitution, on the acceptor splicing site (c.175-1G > C; p.?) in intron 2, and one novel missense mutation (c.1102G > A; p.Glu368Lys), in exon 11. We also report four mutations in the ATP6V0A4 gene: one single nucleotide deletion in exon 13 (c.1221delG; p.Met408Cysfs*10); the nonsense c.16C > T; p.Arg6*, in exon 3; and the missense changes c.1739 T > C; p.Met580Thr, in exon 17 and c.2035G > T; p.Asp679Tyr, in exon 19. CONCLUSION: Molecular diagnosis of ATP6V1B1 and ATP6V0A4 genes was performed in a large Tunisian cohort with dRTA. We identified three different ATP6V1B1 and four different ATP6V0A4 mutations in 25 Tunisian children. One of them, c.1102G > A; p.Glu368Lys in the ATP6V1B1 gene, had not previously been described. Among deaf since childhood patients, 75% had the ATP6V1B1 gene c.1155dupC mutation in homozygosis. Based on the results, we propose a new diagnostic strategy to facilitate the genetic testing in North Africans with dRTA and SNHL.

Polymorphism of C3 complement in association with myocardial infarction in a sample of central Tunisia.

BACKGROUND: Myocardial infarction (MI) is a major clinical problem because of its large contribution to mortality. The genetic bases of this disease have been widely studied in recent years to find a clear association with some genetic markers that increase the risk of its occurrence. In the present investigation, the correlation between MI and the C3 complement polymorphism was analyzed using a case-control study. METHODS: Our study ported on one hundred seventy survived myocardial infarction patients and ninety five healthy controls. The C3 allele identification was investigated using the amplification refractory mutation system PCR to determine the C3*S and the C3*F alleles of the C3 polymorphism. RESULTS: Frequencies of C3*S and C3*F in patients are 0.59 and 0.41 respectively. Fisher test results showed a significant increase of C3*F allele in the sample of patients (0.41; odds ratio: 2.616; C.I [1.738-3.938]) compared to controls (0.21; odds ratio: 0.382; 95% CI [0.254-0.575]), p = 2.742 × 10-6. CONCLUSION: A strong positive correlation was found between C3 polymorphism and MI estimating that the risk of myocardial infarction is significantly increased among patients with C3*F allele of this polymorphism. VIRTUAL SLIDES: The virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/1190484203893646.

PCR-based screening for the most prevalent alpha 1 antitrypsin deficiency mutations (PI S, Z, and Mmalton) in COPD patients from Eastern Tunisia.

It is generally agreed that the protease inhibitor (PI) alleles PI*S (Val264Glu) and PI*Z (Lys342Glu) are the most common alpha 1 antitrypsin deficiency variants worldwide, but the PI*Mmalton allele (ΔPhe52) prevails over these variants in some Mediterranean regions. In eastern Tunisia (Mahdia), we screened 100 subjects with chronic obstructive pulmonary disease for these variants. The PI*S and PI*Z alleles were genotyped by the previously described SexAI/Hpγ99I RFLP-PCR. We provide here a new method for PI*Mmalton genotyping using mismatched RFLP-PCR. These methods are suitable for routine clinical application and can easily be reproduced by several laboratories, since they do not require extensive optimization, unlike the previously described bidirectional allele-specific amplification PCR for PI*Mmalton genotyping. Our results were in agreement with previous reports from central Tunisia (Kairouan), suggesting that the PI*Mmalton mutation is the most frequent alpha 1 antitrypsin deficiency-related mutation in Tunisia.

Research of the origin of a particular Tunisian group using a physical marker and Alu insertion polymorphisms.

The aim of this study was to show how, in some particular circumstances, a physical marker can be used along with molecular markers in the research of an ancient people movement. A set of five Alu insertions was analysed in 42 subjects from a particular Tunisian group (El Hamma) that has, unlike most of the Tunisian population, a very dark skin, similar to that of sub-Saharans, and in 114 Tunisian subjects (Gabes sample) from the same governorate, but outside the group. Our results showed that the El Hamma group is genetically midway between sub-Saharan populations and North Africans, whereas the Gabes sample is clustered among North Africans. In addition, The A25 Alu insertion, considered characteristic to sub-Saharan Africans, was present in the El Hamma group at a relatively high frequency. This frequency was similar to that found in sub-Saharans from Nigeria, but significantly different from those found in the Gabes sample and in other North African populations. Our molecular results, consistent with the skin color status, suggest a sub-Saharan origin of this particular Tunisian group.

Update in chronic obstructive pulmonary disease: role of antioxidant and metabolizing gene polymorphisms.

Chronic obstructive pulmonary disease (COPD) is characterized by systemic and local chronic inflammation and oxidative stress. The sources of the increased oxidative stress in COPD patients derive from the increased burden of inhaled oxidants such as cigarette smoke and other forms of particulate or gaseous air pollution and from the increase in reactive oxygen species (ROS) generated by several inflammatory, immune, and structural airways cells. There is increasing evidence that genetic factors may also contribute to the pathogenesis if COPD, particularly antioxidant genes, which may confer a susceptibility to environmental insults such as cigarette smoke and thereafter development of COPD. Consequently, heme oxygenase-1 (HO-1), superoxide dismutase (SOD), catalase (CAT), glutathione S-transferase (GST), microsomal epoxide hydrolase (EPHX1), and cytochrome P450 (CYP) genetic polymorphisms may have an important role in COPD pathogenesis. In this review the authors summarized the most recent findings dealing with these antioxidant genes contributing to the free radical neutralization and xenobiotic enzymes playing a role in different phases of cell detoxification reactions related to the redox status imbalance in COPD, with an emphasis on their possible roles in disease progression.

Combined analysis of EPHX1, GSTP1, GSTM1 and GSTT1 gene polymorphisms in relation to chronic obstructive pulmonary disease risk and lung function impairment.

Smoking is considered as the major causal factor of chronic obstructive pulmonary disease (COPD). Nevertheless, a minority of chronic heavy cigarette smokers develops COPD. This suggests important contribution of other factors such as genetic predisposing. Our objective was to investigate combined role of EPHX1, GSTP1, M1 and T1 gene polymorphisms in COPD risk, its phenotypes and lung function impairment. Prevalence of EPHX1, GSTP1, M1 and T1 gene polymorphisms were assessed in 234 COPD patients and 182 healthy controls from Tunisia. Genotypes of EPHX1 (Tyr113His; His139Arg) and GSTP1 (Ile105Val; Ala114Val) polymorphisms were performed by PCR-RFLP, while the deletion in GSTM1 and GSTT1 genes was determined using multiplex PCR. Analysis of combinations showed a significant association of 113His/His EPHX1/null-GSTM1 (OR=4.07) and null-GSTM1/105Val/Val GSTP1 (OR =3.56) genotypes with increased risk of COPD (respectively P=0.0094 and P=0.0153). The null-GSTM1/ null-GSTT1, 105Val/Val GSTP1/null GSTT1, 113His/His EPHX1/null-GSTM1 and null-GSTM1/105Val/Val GSTP1 genotypes were related to emphysema (respectively P=0.01; P=0.009; P=0.008 and P=0.001). Combination of 113His/His EPHX1/null-GSTM1 genotypes showed a significant association with the decrease of Δ FEV1 in patients (P =0.028).In conclusion, our results suggest combined EPHX1, GSTP1, GSTM1 and GSTT1 genetic polymorphisms may play a significant role in the development of COPD, emphysema and decline of the lung function.

Correlation of EPHX1, GSTP1, GSTM1, and GSTT1 genetic polymorphisms with antioxidative stress markers in chronic obstructive pulmonary disease.

This study was undertaken to ascertain if a relationship existed between oxidative status and polymorphisms of microsomal epoxide hydrolase X1 (EPHX1), glutathione S-transferase P1 (GSTP1), GSTM1, and GSTT1 in chronic obstructive pulmonary disease (COPD). Erythrocyte glutathione peroxidase (GSH-px), glutathione reductase (GR), superoxide dismutase (SOD), catalase (CAT), and plasma GST activities and total antioxidant status (TAS) as antioxidative stress markers were determined and compared either with individual and combined genotypes of EPHX1 exon 3, GSTP1 exon 5, GSTM1, and GSTT1 polymorphisms in COPD patients and healthy controls from the central area of Tunisia. Statistical data processing revealed significantly lower GSH-px, GR, SOD, CAT, GST, and TAS values in COPD patients in comparison to the control group (P < .001). As for genotypes, there was a no significant association in each of the 6 parameters and individual genotypes (P > .05). A significant correlation between the studied parameters and combined null GSTM1/null GSTT1 (GSH-px: P < .001, GR: P = .026, CAT: P = .018, GST: P = .022, TAS: P = .046), His113His EPHX1/null GSTM1 (GSH-px: P = .001, GST: P = .0012, TAS: P = .013), His113His EPHX1/Val105Val GSTP1 (GSH-px: P = .048, CAT: P = .026, GST: P = .031), and null GSTM1/Val105Val GSTP1 (GSH-px: P = .011, GR: P = .0028, GST: P = .0054, TAS: P = .032) was found in patients. In conclusion, combined genetic polymorphisms of GSTM1, GSTT1, GSTP1, and EPHX1 may have favorable effects on redox balance in COPD patients.

Xmn I polymorphism associated with concomitant activation of Gγ and Aγ globin gene transcription on a ß0-thalassemia chromosome.

The -158 (C→T) nucleotide change, known as Xmn I polymorphism, occurs in (G)γ-globin gene promoter, and results in elevated fetal hemoglobin (HbF). We found this mutation in cis of a ß(0)-thalassemia splicing mutation. Despite the complete absence of adult HbA, the phenotype was only moderately severe with no detectable alteration of α-globin gene expression. Interestingly, the ß-globin locus haplotype has not been described to bear the (G)γ promoter mutation. Using a gene-specific real-time RT-PCR approach, we found a dramatic increase of both (G)γ and (A)γ mRNA accumulated in the reticulocytes, suggesting that the (G)γ-promoter mutation, alone or in association with another genetic modification, alters in concert the transcription of both (G)γ and (A)γ. This observation is discussed in light of recent regulatory model for ß-globin locus.

Atypical hemolytic uremic syndrome in the Tunisian population.

BACKGROUND: Hemolytic uremic syndrome consists of a triad of acquired hemolytic anemia, thrombocytopenia and renal failure. AIM: Our objectives were to determine epidemiology, clinical and laboratory characteristics of patients with atypical hemolytic uremic syndrome (aHUS) to determine the relationship between the complement protein deficit and aHUS in the Tunisian population. METHODS: We studied retrospectively four cases of atypical HUS in adults admitted in the Nephrology Department of Fattouma Bourguiba Universitary Hospital in Monastir between 2000 and 2008. RESULTS: Three patients had renal failure that required dialysis. One of them received kidney transplantation with no further recurrence of aHUS. Three patients had normal C3, C4, CFH, and FB levels, and in all patients anti-FH autoantibodies were absent. The kidney biopsy of one patient showed in addition to lupus glomerulonephritis histological findings consistent with TMA. A decrease in C3, C4 and CFH levels in this patient was found both before and after the cure. CONCLUSION: Nephrologists should be aware of autoimmune conditions and genetic abnormalities of the complement regulatory genes as possible pathogenic mechanisms in atypical HUS patients.

Research of the origin of a particular Tunisian group using a physical marker and Alu insertion polymorphisms

The aim of this study was to show how, in some particular circumstances, a physical marker can be used along with molecular markers in the research of an ancient people movement. A set of five Alu insertions was analysed in 42 subjects from a particular Tunisian group (El Hamma) that has, unlike most of the Tunisian population, a very dark skin, similar to that of sub-Saharans, and in 114 Tunisian subjects (Gabes sample) from the same governorate, but outside the group. Our results showed that the El Hamma group is genetically midway between sub-Saharan populations and North Africans, whereas the Gabes sample is clustered among North Africans. In addition, The A25 Alu insertion, considered characteristic to sub-Saharan Africans, was present in the El Hamma group at a relatively high frequency. This frequency was similar to that found in sub-Saharans from Nigeria, but significantly different from those found in the Gabes sample and in other North African populations. Our molecular results, consistent with the skin color status, suggest a sub-Saharan origin of this particular Tunisian group.

Microsomal epoxide hydrolase gene polymorphisms and susceptibility to chronic obstructive pulmonary disease in the Tunisian population.

It is well known that cigarette smoking is the major risk factor for chronic obstructive pulmonary disease (COPD). However, only 10%-20% of chronic heavy cigarette smokers develop symptomatic disease, which suggests the presence of genetic susceptibility. Microsomal epoxide hydrolase (EPHX1) is an enzyme involved in the protective mechanism against oxidative stress. It has been reported that gene polymorphisms of this enzyme may be associated with variations in EPHX1 activity. In this study, we aimed at investigating the relationship between EPHX1 polymorphisms and susceptibility to COPD in the Tunisian population. EPHX1 exon 3 (rs1051740, Tyr113His) and exon 4 (rs2234922, His139Arg) polymorphisms were genotyped by polymerase chain reaction followed by restriction fragment length polymorphism analysis. These techniques were used to examine a total of 416 Tunisian individuals, including 182 blood donors and a group of 234 COPD patients. All subjects were not related. An increased risk for COPD was observed in subjects with EPHX1 His113-His113 genotype (odds ratio = 2.168; confidence interval 1.098-4.283; p = 0.02386). However, multivariate logistic regression analysis showed no significant relationship between the mutant genotype and the disease after adjustment for sex, age, body mass index, smoking status, and pack-year smoking (odds ratio = 1.524; confidence interval, 0.991-6.058; p = 0.06137). Regarding the two subtypes of COPD, our investigations demonstrated that there is no significant correlation between exon 3 polymorphism and the chronic bronchitis subgroup (p = 0.09034). The relation between exon 3 polymorphism and emphysema was significant in the univariate analysis (p = 0.02257), but no association was found after controlling for classic risk factors (p = 0.06273). In conclusion, our results showed that there is a weak relation between 113His genotype and COPD, and no apparent relation between 139Arg and COPD in the studied Tunisian population.

Association of GSTM1 and GSTT1 polymorphisms with chronic obstructive pulmonary disease in a Tunisian population.

GSTM1 and GSTT1 polymorphisms have been proposed in relationship with chronic obstructive pulmonary disease (COPD). We investigated the association between these polymorphisms and COPD (as well as its subtypes emphysema and chronic bronchitis) in 234 COPD patients and 182 healthy controls in the Tunisian population. Genotyping was performed using multiplex PCR. GSTM1-null genotype frequency was significantly higher in COPD patients than in controls (P = 0.02); however, multivariate analysis of cofounding variables showed no independent association with this genotype (P = 0.073). In contrast, the association of the GSTM1-null genotype with emphysema was significant, even after adjustment for risk factors (P = 0.011). There were no significant differences in GSTT1 genotypes between patients and controls. The GSTM1 null allele is likely not an independent risk factor for COPD but is related to emphysema, whereas the GSTT1 gene is not associated with the disease.

Hemoglobinopathies in North Africa: a review.

Hemolytic anemias are very common diseases. Among these diseases, hemoglobinopathies are widely spread throughout the Mediterranean Basin, including North Africa (Tunisia, Algeria and Morocco). Their severity and disabling nature make them a major public health problem. This study includes our data on the Tunisian hemoglobinopathies together with all the reports concerning epidemiological, clinical and molecular aspects in Algerian and Moroccan populations. Investigation methods begin with the application of several techniques for hemoglobin (Hb) analyses [electrophoresis and isoelectric focusing (IEF), micro-chromatography assay] of anemic patients in various hospital departments. Molecular investigation by DNA analyses completes the hematological and biochemical studies using polymerase chain reaction (PCR) followed by enzymatic digestion and/or denaturing gradient gel electrophoresis (DGGE), single strand conformation polymorphism (SSCP) and sequencing. These methods offer screening for a large number of families affected by sickle cell disease and thalassemia. In Tunisia, Algeria, and Morocco, more than 45 mutations have been identified on the beta-globin gene. The most common in Tunisia and in Algeria are codon 39 (C>T) and IVS-I-110 (G>A), which together account for more than 50% of all mutations. In Morocco, the predominant mutations are codon 39 and frameshift codon (FSC) 8 (-AA). The identification of molecular defects in the betagene contributes to the development of diagnostic tests (prenatal diagnosis), and gives us the opportunity to help many couples. Our studies of the haplotypes of the beta(S), codon 39 and IVS-I-110 origins allowed the hypothesis of a Benin origin for beta(S), a local North African origin for codon 39 and an Eastern Mediterranean origin for IVS-I-110. The analysis of polymorphisms associated with a moderate phenotype of beta-thalassemia (beta-thal) and sickle cell disease in North Africa has shown, in several cases, a strong association with some mutations and restriction fragment length polymorphisms (RFLP) haplotype IX on the beta-globin locus and the -158 (C>T) polymorphism in 5' on the (G)gamma-globin gene. Finally, more knowledge on the regulation of the beta-globin locus may contribute to the improvement of investigation, monitoring and treatment of hemoglobinopathies.