Rendrik F. Franco

The methylenetetrahydrofolate reductase C677T gene polymorphism decreases the risk of childhood acute lymphocytic leukaemia

We have determined the prevalence of methylenetetrahydrofolate reductase (MTHFR) mutations C677T and A1298C in 71 children ( 15 years) with acute lymphoblastic leukaemia (ALL) and in 71 control subjects. Odds ratio (OR) for ALL linked to MTHFR C677T was 0·4 (95% CI 0·2–0·8); for heterozygotes it was 0·5 (95% CI 0·2–0·9) and for homozygotes it was 0·3 (95%CI 0·09–0·8). MTHFR A1298C yielded an overall OR for ALL of 1·3 (95% CI: 0·7–2·6); for heterozygotes it was 1·3 (95% CI: 0·7–7·6) and for homozygotes it was 2·8 (95% CI 0·5–15·6). In conclusion, MTHFR C677T was linked to a significant 2·4‐fold decreased risk of developing childhood ALL, whereas MTHFR A1298C did not significantly affect the risk of ALL in our population.

The 20210 G→ A mutation in the 3'-untranslated region of the prothrombin gene and the risk for arterial thrombotic disease

A sequence variation in the 3′‐untranslated region of the prothrombin (PT) gene (20210 G → A) was recently claimed to be associated with elevated plasma prothrombin levels and an increased risk for venous and arterial thrombosis. We examined the prevalence of the 20210 A allele in the prothrombin gene in 400 healthy controls and in 263 patients with proven premature atherosclerotic disease. In addition, we measured prothrombin, prothrombin fragment 1 + 2, thrombin–antithrombin (TAT) complex and D‐dimer levels in plasma from carrier and non‐carrier patients. The frequency of the variant allele was 1% in the control subjects and 2.7% in the patient group, yielding a relative risk (RR) for the 20210 A allele of 2.7 (95% CI 0.8–9.4). All heterozygotes in the patient group were found to have had a myocardial infarction (MI), yielding a RR for MI of 4.2 (95% CI 1.2–14.6). Plasma prothrombin levels in carriers (126 ± 10) were higher than in non‐carriers (103 ± 1, P = 0.02). The levels of TAT complexes (16 ± 9 v 6 ± 1 μg/ml, P = 0.02) as well as of prothrombin fragment 1 + 2 (1.5 ± 0.3 v 1.0 ± 0.1 nmol/l, P = 0.02) were also elevated in carriers of the mutation. Our findings suggest that the 20210 G → A mutation in the prothrombin gene is a genetic risk factor for MI. In addition, our data provide evidence for an association of the mutation with excessive thrombin generation, which may contribute to the understanding of its role in venous and arterial disease.

Gene polymorphisms in the TNF locus and the risk of myocardial infarction

We investigated two genetic polymorphisms in the tumor necrosis factor locus (TNF-alpha -308 G-->A and LT-alpha +252 A-->G) as risk factors for coronary atherothrombotic disease (CAD) by determining its prevalence in 148 survivors of myocardial infarction (MI) with angiographically-proven severe CAD, and in 148 age-, gender- and race-matched controls. The odds ratio (OR) for MI related to the mutant TNF-alpha and LT-alpha alleles was 0.8 (CI95: 0.4-1.3) and 1. 3 (CI95: 0.8-2.0), respectively. We also sought interaction of smoking and metabolic risk factors for MI with each mutant genotype. Smokers not carrying the LT-alpha +252 A-->G mutation had a risk of MI of 2.7 (CI95: 1.4-5.4) whereas in smoking carriers the risk was 6. 9 (CI95: 3.4-14.1). An interactive effect of the LT-alpha mutation may also exist with dyslipidemia (OR for MI in non-carriers was 12 [CI95: 3.2-41.3] and in carriers the OR was 39, [CI95: 5.1-301] and with obesity (OR for MI was 2.7, [CI95: 1-7.2] in non-carriers and in carriers the OR was 6 [CI95: 2.1-16.8]). Lastly, the OR for MI in obese non-carriers of TNF-alpha -308 G-->A was 2.8 (CI95: 1.3-6) and in obese carriers the OR was 14.5 (CI95: 1.8-113). Although significant interactive effects could not be detected, the findings suggest that interaction of polymorphisms in the TNF locus with major risk factors for CAD may exist, and should be explored in larger studies.

Are Haemochromatosis Mutations Related to the Severity of Liver Disease in Hepatitis C Virus Infection

It has been proposed that iron overload may adversely affect liver disease outcome. The recent identification of 2 mutations in the HFE gene related to hereditary haemochromatosis (Cys282Tyr and His63Asp) provided an opportunity to test whether they are associated with hepatic iron accumulation and the activity and severity of liver disease in hepatitis C virus (HCV) infection. We investigated the prevalence of HFE mutations in 135 male patients with chronic HCV hepatitis, and correlated genotype distribution with different parameters of iron status and the activity and severity of liver disease. Of these 135 patients, 6 (4.4%) carried Cys282Tyr and 32 (23.7%) carried His63Asp, frequencies which were similar to those observed in healthy controls. Serum iron levels and transferrin saturation (but not ferritin levels or liver iron content) were significantly higher in carriers than in non-carriers of HFE mutations. No difference was observed in serum ALT, AST and GGT levels between carriers and non-carriers. Finally, scores for necroinflammatory activity and fibrosis in the liver were significantly higher in HFE carriers than in non-carriers. Patients with chronic HCV infection carrying HFE mutations tend to present more evident body iron accumulation and a higher degree of necroinflammatory activity and fibrosis in the liver. HFE gene mutations might be an additional factor to be considered among those implicated in the determination of a worse prognosis of the liver disease in chronic HCV infection.

Microvascular coagulopathy and disseminated intravascular coagulation.

ObjectiveTo review the dual characteristics of disseminated intravascular coagulation (DIC), as both a contributor to multiple organ failure as well as a symptom of severe underlying disease associated with systemic vascular changes. Data SourcesPublished literature data and unpublished results from the authors. Data SummaryClinical and experimental studies strongly suggest that DIC contributes to multiple organ failure and death in patients with severe systemic disorders such as sepsis. DIC is evoked by systemic cytokine activity, and the inflammatory response aggravates vascular permeability, inflammation, and cell damage in tissues. In addition to intravascular fibrin formation, thrombin and fibrin generation in tissues is also an important aspect of DIC. An example of DIC at the organ level is adult respiratory distress syndrome, where fibrin in the lung is a characteristic feature. Intravascular fibrin formation and occlusion may elicit a hypoxic response with induction of hypoxia related transcription factors. The resulting ischemic preconditioning may offer protective effects to the involved organ(s). ConclusionsOverall, the beneficial or harmful effects of activated coagulation and fibrin formation for organ pathology and recovery from DIC remain to be explored. This may be a critical element in the assessment of ischemia-reperfusion effects of specific anticoagulant therapy.

Prevalence of the G20210A polymorphism in the 3'-untranslated region of the prothrombin gene in different human populations.

Recently a novel polymorphism in the 3′-untranslated region of the prothrombin gene (a G to A transition at position 20210) was discovered, and an association with venous thrombosis and cardiovascular disease was found. The prevalence of the polymorphic allele in different human populations is unknown. We investigated the prevalence of the A 20210 allele of the prothrombin gene in 420 unrelated individuals (840 chromosomes) who belong to four different ethnic groups: Whites, African and Brazilian Blacks, Asians and Amerindians. PCR amplification followed by HindIII digestion was employed. The polymorphism was found in heterozygosity in 2 out of 120 Whites or a prevalence of 1.6% (allele frequency 0.8%), similar to that observed for other Caucasian populations. The A allele was absent among the other ethnic groups analyzed. Our data indicate that in non-Caucasians the prevalence of the 20210 G→A mutation in the prothrombin gene, if any, must be extremely low. The absence of this novel genetic risk factor for venous and arterial thrombotic disease among non-Caucasians may contribute to explaining geographical and ethnic differences in the risk of vascular disease.

A second mutation in the methylenetetrahydrofolate reductase gene and the risk of venous thrombotic disease

We assessed the effect of a recently described mutation in the MTHFR gene (1298 A → C) on the risk of deep venous thrombosis (DVT) by determining its prevalence in 190 patients with verified DVT and in age‐, race‐ and gender‐matched controls. MTHFR 1298 A → C was found in 42.1% of patients and in 41.1% of controls. The OR for venous thrombosis was 1.07 (95% CI 0.70–1.65) for heterozygotes and 0.83 (95% CI 0.33–2.08) for homozygotes. The OR for the factor V Leiden (FVL) mutation was 3.40 (95% CI 1.22–9.48), for FII 20210 G → A was 5.22 (95% CI 1.12–24.2) and for MTHFR 677 C → T, 1.24 (95% CI 0.82–1.87). No significant increased risk for venous thrombosis was found when MTHFR 1298 A → C was coinherited with FVL (OR 2.85, 95% CI 0.88–9.23), FII 20210 G → A (OR 7.19, 95% CI 0.87–59.4) or MTHFR 677 C → T (OR 1.44, 95% CI 0.71–2.92). These data do not support a critical role of MTHFR 1298 A → C in the predisposition to DVT.

Prevalence of factor V Leiden, FII G20210A, FXIII Val34Leu and MTHFR C677T polymorphisms in cancer patients with and without venous thrombosis

Venous thromboembolism (VTE) is a common complication in patients with malignant disease. In addition to well-established acquired risk factors for VTE, several genetic risk factors, mainly related to the haemostatic system, are known to influence thrombotic risk. However, the contribution of gene abnormalities to thrombotic tendency in cancer patients remains poorly explored. We performed a prospective study to evaluate the prevalence and clinical significance of four gene variations (factor V Leiden [FVL], factor II G20210A, factor XIII Val34Leu and MTHFR C677T) in cancer patients, with and without VTE. Enrolled were 211 unrelated and unselected patients (M/F ratio 0.5, mean age 57 years, range 12-91 years) with a diagnosis of cancer, admitted to two University Oncology Clinics in the city of São Paulo, Southeastern Brazil. After admission, all patients were evaluated for the presence of symptoms and signs of VTE. Sixty-four patients (30.3%) had an episode of deep venous thrombosis (DVT) or pulmonary embolism (PE), which has been objectively verified; 147 patients (69.7%) had no evidence of VTE. FVL was found with a frequency of 1.5% and 2.7% in the VTE and non-VTE group, respectively (odds ratio [OR] for VTE 0.6, 95% CI: 0.06-5.3). FII G20210A was found in 1.5% and 1.3% of thrombotic and nonthrombotic patients, respectively, yielding an OR of 1.2 (95% CI: 0.1-13.1). FXIII Val34Leu was detected in 29.6% of the thrombotic patients and in 28.5% of the non-thrombotic patients (OR 1.1, 95% CI: 0.5-2). MTHFR 677T was present in 53.1% and 60.5% of patients with and without thrombosis, respectively (OR 0.8, 95% CI: 0.4-1.4). The present data do not point to an association between the four polymorphisms here investigated and the risk of VTE in cancer patients.

Porphyria cutanea tarda in Brazilian patients: association with hemochromatosis C282Y mutation and hepatitis C virus infection

OBJECTIVE:Porphyria cutanea tarda (PCT) is commonly associated with iron overload and hepatitis C virus (HCV) infection. Association between hemochromatosis C282Y or H63D mutations and PCT has been observed, although not uniformly, and iron overload is also commonly found in chronic HCV hepatitis. The aim of the present study was to investigate the frequency of C282Y and H63D mutations and HCV infection in Brazilian patients with PCT and their relationship with iron overload.METHODS:Twenty-three patients (19 men) aged 39.6 ± 11.1 yr were studied. All had dermatological lesions of PCT and high levels of urinary uroporphyrin. HCV infection and iron overload were investigated. DNA samples were analyzed for the presence of HFE mutations.RESULTS:The frequency of C282Y was significantly higher in PCT patients than in 278 healthy individuals (17.4% vs 4%, odds ratio = 5.1, 95% confidence interval 1.5–17.6, p= 0.02), whereas no difference was observed regarding the H63D mutation (30.4% vs 31%, odds ratio = 1, 95% confidence interval 0.4–2.4, p= 1). Biochemical tests in PCT patients showed iron overload with transferrin saturation = 47.3 ± 20.7% and ferritin = 566.8 ± 425 ng/ml. Fifteen of 23 (65.2%) patients had HCV infection and alcohol ingestion was observed in 17 of 23 (73.9%).CONCLUSIONS:PCT patients exhibited evidence of iron overload, a high frequency of HCV, and an association with C282Y mutation. These data further support the notion that both acquired and inherited factors contribute to the occurrence of PCT, and indicate that screening for C282Y may be justified in PCT patients.

Liver iron deposits in hepatitis B patients: association with severity of liver disease but not with hemochromatosis gene mutations.

Background and Aims:  Iron deposits in the liver and abnormalities in serum iron biochemistry are frequently observed in patients with chronic liver diseases, but data for patients with hepatitis B virus (HBV) infection are scarce. Moreover, the role of HFE mutations in iron deposits in this condition remains unknown. The aim of the present study was to determine the prevalence of serum iron biochemical abnormalities and iron deposits in the liver of chronic HBV patients, and to evaluate the consequences for the activity and severity of liver disease. Additionally, we studied the role of HFE gene mutations in iron deposits.