Marli H. Tavella

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.

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.

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.

Heterogeneous Ethnic Distribution of the 844ins68 in the Cystathionine β-Synthase Gene

A novel mutation in the cystathionine β-synthase (CBS) gene (a 68-bp insertion in the coding region of exon 8: 844ins68) was recently described, but its prevalence in different human populations is unknown. We analyzed the prevalence of the 68-bp insertion in the CBS gene in 405 unrelated individuals (810 chromosomes) of European, African, Asian and Amerindian origins. PCR amplification of a DNA fragment containing exon 8 of the CBS gene was employed. In addition, screening for the T833C CBS mutation by BsrI digestion was carried out in all samples bearing the 844ins68 mutation, since both mutations were previously reported to be associated in cis. The insertion was found in heterozygosity in 14 out of 104 whites (13.5%), was absent among Asians, and was found solely in 1 out of 220 Amerindian chromosomes analyzed, whereas a much higher prevalence was observed among blacks (37.7% of heterozygotes and 4% of mutant homozygotes). Furthermore, the T833C CBS mutation was found to cosegregate in cis with 844ins68 in all carriers of the insertion. The finding of the double mutant among blacks and Caucasians suggests that it antedated the racial divergence between Africans and non-Africans, and provides evidence for a partly or completely neutralizing effect conferred by the 68-bp insertion, since it allows the skipping of the T833C mutation. Our study represents the first analysis of the 844ins68 insertion in the CBS gene in different human populations, and reveals an extensive ethnic and geographic variability associated with this mutation.

Factor V Arg306 Thr (factor V Cambridge) and factor V Arg306 Gly mutations in venous thrombotic disease

We investigated the prevalence of two reported mutations of the factor V gene (factor V Arg306 → Thr, or factor V Cambridge, and factor V Arg306 → Gly) in 104 relatively young patients with verified venous thrombosis and in 208 age‐, sex‐ and race‐matched controls, in order to establish whether the two mutations are associated with increased predisposition for venous thrombosis. PCR amplification followed by BstNI and MspI digestion was employed to determine the genotypes, and each mutation was confirmed by DNA sequencing. Among the controls, one individual was found to be heterozygous for the factor V Arg306 → Thr mutation and one heterozygous for the factor V Arg306 → Gly mutation; none of the patients carried either mutation. Our findings do not support factor V Cambridge and factor V Arg306 → Gly as risk factors for venous thrombosis.

Absence of the E2 allele of apolipoprotein in amerindians

Determination of the ApoE allele distribution in five South American Amerindian tribes revealed absence of the ApoE2 allele, accompanied by high ApoE3 and low ApoE4 allele frequencies for most tribes, a distribution only previously reported for the Inuit Eskimo from Greenland.

Heterogeneous ethnic distribution of the factor v leiden mutation

Resistencia a proteina C ativada associada a mutacao do fator V Leiden (FVL) e a mais prevalente causa genetica de trombose venosa conhecida, sendo encontrada em 20 a 60% dos pacientes com trombofilia. Adicionalmente, uma associacao entre a mutacao do FVL e predisposicao aumentada para doenca cardiovascular prematura em mulheres foi recentemente descrita. No presente estudo nos determinamos a prevalencia da mutacao do FVL em 440 individuos (880 cromossomos) de 4 grupos etnicos diferentes: caucasoides, negros africanos, asiaticos e amerindios. Amplificacao por PCR seguida de digestao com a enzima de restricao MnlI foi utilizada para definicao do genotipo. A mutacao do FVL foi encontrada em heterozigose em 4 de 152 caucasoides (2,6%), 1 de 151 amerindios (0,6%) e esteve ausente em 97 negros africanos e 40 asiaticos. Nossos resultados confirmam que o FVL apresenta distribuicao heterogenea em diferentes populacoes humanas, fato que pode contribuir para diferencas etnicas e geograficas na prevalencia de doencas tromboticas. Adicionalmente, estes dados podem ser uteis para a definicao de estrategias de rastreamento desta mutacao em individuos sob risco para desenvolvimento de trombose, na populacao brasileira.

Prevalence of hereditary risk factors for thrombophilia in Belém, Brazilian Amazon

Different risk factors for venous thromboembolism (VTE) have been identified, including hereditary abnormalities in the mechanisms of coagulation and fibrinolysis. We investigated five genetic polymorphisms (FVL G1691A, FII G20210A, MTHFR C677T, TAFI A152G and TAFI T1053C) associated with VTE in individuals from the city of Belem in the Brazilian Amazon who had no history of VTE. No significant difference was found between the observed and expected genotype frequencies for the loci analyzed. We found high frequencies of MTHFR C677T (33.9%) and TAFI T1053C (74%) and low frequencies of FVL (1.6%), FII G20210A (0.8%) and TAFI A152G (0.8%). The FVL G1691A, FII G20210A and MTHFR C677T frequencies were similar to those for European populations and populations of European descent living in the city of Ribeirao Preto in the Brazilian state of Sao Paulo. The frequency of the two TAFI mutations in the Belem individuals was not significantly different from that described for individuals from Ribeirao Preto. We suggest that the risks for VTE in the population of Belem are of the same magnitude as that observed in European populations and in populations with an expressive European contribution.