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.

Elevated TS and liver iron deposits were frequent in non-cirrhotic HBV patients. Iron deposits were mainly mild and associated with higher activity and severity of liver disease, but not with HFE mutations.

The allele frequencies of six VNTRs (D1S80, D4S43, ApoB 3’ VNTR, von Willebrand factor VNTR-I, DXS52 and DYS19) in 123 Amerindians from five tribes (Arara, Wayana-Apalai, Wayampi, Yanomama and Kayapo) were compared with three other Brazilian populations: Whites, Blacks, and individuals of Japanese extraction. The data clearly distinguished the four populations, and measurements of diversity show a decreasing average heterozygosity from Blacks to Whites, Japanese, and Indians. Seven novel alleles were observed; amongst them, two small DYS19 alleles and a large D4S43 allele occurred only in Indians, and may be useful genetic markers for this population. Other prominent features of the Amerindians were: (1) high frequency of ApoB allele 46; (2) absence of a shorter variant of D4S43 allele 1; (3) high frequency, limited to one tribe, of allele 12 of the von Willebrand VNTR. The study also demonstrated a heterogeneity of the Indian tribes, due to both different allele frequencies and the presence or absence of specific alleles. Gst was 0.106 for the five Indian populations, and 0.065 for Whites, Blacks and Japanese. H_S and H_T demonstrated that 11 % of the total diversity among Amerindians is caused by interpopulational variability, as compared with 7% for the other three racial groups. In contrast, diversity within each tribe is usually low, as demonstrated by a low average number of alleles per locus. These findings indicate that the study of a small number of tribes may not be representative of the variability of Amerindians, even if a large number of individuals are studied. To capture the whole range of genetic variability of Amerindians, it is necessary to study a large number of populations. The limited genetic diversity thus far observed for Amerindians seems to reflect both a genuine decrease of diversity and a bias caused by the study of limited numbers of tribes.

The majority of the chromosomes with the ␤ S gene have one of the five common haplotypes, designated as Benin, Bantu, Senegal, Cameroon, and Arab-Indian haplotypes. However, in every large series of sickle cell patients, 5-10% of the chromosomes have less common haplotypes, usually referred to as "atypical" haplotypes. In order to explore the genetic mechanisms that could generate these atypical haplotypes, we extended our analysis to other rarely studied polymorphic markers of the ␤ S -gene cluster, in a total of 40 chromosomes with uncommon haplotypes from Brazil and Cameroon. The following polymorphisms were examined: seven restriction site polymorphisms of the ␥␦␤-cluster, the pre-G ␥ framework sequence including the 6-bp deletion/insertion pattern, HS-2 LCR (AT)xR(AT)y and pre-␤ (AT)xTy repeat motifs, the GC/TT polymorphism at −1105-1106 of G ␥-globin gene, the C/T polymorphism at −551 of the ␤-globin gene, and the intragenic ␤-globin gene framework. Among the Brazilian subjects, the most common atypical structure (7/16) was a Bantu 3-subhaplotype associated with different 5-sequences, while in two chromosomes a Benin 3-subhaplotype was associated with two different 5-subhaplotypes. A hybrid Benin/Bantu configuration was also observed. In three chromosomes, the atypical haplotype differed from the typical one by the change of a single restriction site. In 2/134 chromosomes identified as having a typical Bantu RFLPhaplotype, a discrepant LCR repeat sequence was observed, probably owing to a crossover 5 to the -gene. Among 80 ␤ S chromosomes from Cameroon, 22 were associated with an atypical haplotype. The most common structure was represented by a Benin haplotype (from the LCR to the ␤-gene) with a non-Benin segment 3 to the ␤-globin gene. In two cases a Bantu LCR was associated with a Benin haplotype and a non-Benin segment 3 to the ␤-globin gene. In three other cases, a more complex structure was observed that can be considered as a hybrid of Benin, Bantu, Senegal, or other chromosomes was observed. These data suggest that the atypical ␤ S haplotypes are not uncommon in America and in Africa. These haplotypes are probably generated by a variety of genetic mechanisms including (a) isolated nucleotide changes in one of the polymorphic restriction sites, (b) simple and double crossovers between two typical ␤ S haplotypes or much more frequently between a typical ␤ S haplotype and a different ␤ Aassociated haplotype that was present in the population, and (c) gene conversions. Am.

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 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.

Summary.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%

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.