Clinical, biochemical and genetic characteristics of Variegate Porphyria in Italy.

Variegate Porphyria (VP) is an autosomal dominant disorder found worldwide but is rare in Italy. In this study we provide an overview of clinical, biochemical and genetic background of 33 Italian VP patients diagnosed in the last fifteen years. About 70% of patients had experienced clinical symptoms: 43.4% had photosensivity, 8.7% acute attacks and 47.8% both. Among the 33 patients, 14 different mutations were identified. Of these only 6 defects have been previously described in other countries and 8 are unique having been identified for the first time in Italy. Two of these, the c.851G>T and the c.1013C>G, were found in two and four unrelated families respectively. No mutation has been found in homozygosis and no significant correlation has been observed between specific clinical and biochemical manifestations and the type of mutation. In contrast, normal faecal protoporphyrin excretion was high predictive of silent phenotype. Normal urinary excretion of PBG and ALA, predicted absence of neurovisceral symptoms. This paper represents the first compilation of data on genotype-phenotype relation in Italian patients with VP.

Seven novel point mutations in the uroporphyrinogen decarboxylase (UROD) gene in patients with familial porphyria cutanea tarda (f-PCT).

In this work, we describe seven novel molecular defects in the uroporphyrinogen decarboxylase gene responsible for familial porphyria cutanea tarda in Italian subjects with reduced erythrocyte URO-D activity. Four of these molecular abnormalities (R142Q, L161Q, S219F, P235S) are missense mutations, one (Q206X) is a nonsense mutation, one (IVS8-1 G>C) is a splicing defect causing the exon 9 deletion and one (1107 G>A) is located in the 3' untranslated region of UROD gene. All the amino acid substitutions fall in conserved regions in several organisms suggesting an important role in catalysis or in the protein structure stabilization. Three of these mutations have been detected in more than one subject. These results suggest a molecular heterogeneity at the UROD locus in Italian PCT patients although recurrent mutations have been identified.

Membrane-bound iron contributes to oxidative damage of beta-thalassaemia intermedia erythrocytes.

Iron-dependent oxidative reactions in beta-thalassaemic erythrocyte membranes are involved in premature cell removal and anaemia. We studied 22 beta-thalassaemia intermedia patients (i) to assess if membrane iron accumulation influences the oxidative damage to thalassaemic cells, and (ii) to see whether the mechanisms of haemoglobin destabilization described in vitro have indicators in circulating erythrocytes. Serum non-transferrin-bound iron as potentially toxic iron for erythrocytes was also evaluated. Membrane-bound free iron significantly correlated to bound haemichromes, suggesting a causal relation, but was poorly related to serum non-transferrin iron, which seems to contribute little to damage from outside the cells. The spleen played an important role in the removal of cells with more membrane iron.

Molecular characterisation of the glucose-6-phosphate dehydrogenase (G6PD) Ferrara II variant.

During the last ten years, molecular biological techniques such as cloning and sequencing and, more recently, polymerase chain reaction (PCR) amplification have led to the identification of the molecular defects responsible for more than fifty glucose-6-phosphate dehydrogenase (G6PD) variants. In this paper, we report the identification of the molecular abnormality underlying the G6PD Ferrara II variant, present in the Po delta area of Northern Italy. Biochemical characterisation shows an enzymatic activity of about 15% of normal (WHO class III), slow electrophoretic mobility, low Km for G6P, high percentage substrate analogue utilisation and a biphasic pH optimum curve. After PCR amplification, non-radioisotopic single-strand conformation polymorphism analysis carried out for the entire coding region has revealed a mobility shift in exon 8. Nucleotide sequencing has demonstrated a missense 844 G > C mutation, causing an Asp > His amino-acid replacement, known as being responsible for G6PD Seattle, G6PD Modena and G6PD Lodi.

Rapid isolation of glucose-6-phosphate dehydrogenase from human erythrocytes by combined affinity and anion-exchange chromatography for biochemical characterization of variants.

A new method is presented for the purification of human glucose-6-phosphate dehydrogenase (G6PD) using affinity chromatography with 2'5'-ADP-Sepharose 4B followed by automated ion-exchange chromatography with DEAE 5PW. This rapid method allows a high recovery of enzyme activity from even a small amount of blood; the yield is about 90% after the first purification step and 70% at the end of the procedure. There is an excellent reproducibility of the kinetic parameters and optimal biochemical characterization of G6PD is achieved even for variants associated with severe enzyme deficiency (e.g. G6PD Mediterranean).

Molecular heterogeneity of glucose-6-phosphate dehydrogenase (G6PD) variants in Italy.

BACKGROUND: Glucose-6-phosphate dehydrogenase deficiency, one of the most common human enzymatic defects, is characterized by extreme molecular and biochemical heterogeneity. The molecular bases of almost all polymorphic italian variants have now been identified and the overall heterogeneity is lower than expected from biochemical data. METHODS: We examined 161 G6PD-deficient subjects (130 males and 31 females) originating from different parts of Italy. G6PD activity and molecular characterization were determined in all the subjects analyzed. RESULTS: We found the G6PD Mediterranean genotype in roughly 70%, G6PD Union and G6PD Seattle in about 6% and G6PD A- in 4% of the samples analyzed. G6PD S. Antioco and G6PD Cosenza were less frequent (1.2%), and single cases of G6PD Partenope and G6PD Tokyo were also detected. CONCLUSIONS: We report the frequency and distribution of the most common G6PD variants in Italy. Greater molecular heterogeneity than described by others was observed, especially in Sardinia. Among the severe deficient variants, G6PD Mediterranean has a higher prevalence in Sardinia (83%) than in continental Italy (61%), as does G6PD Union (10% and 4%, respectively). G6PD Seattle and A-, associated with mild G6PD deficiency, are by contrast more frequent in continental Italy.

Indices of membrane alterations in beta-thalassemic erythrocytes.

Analytical protocols for the study of thalassemic erythrocyte membrane alterations are described. Denatured hemoglobin derivatives and aggregated band 3 are separated from detergent membrane extracts by gel-filtration as high-molecular-weight aggregates and quantitated spectrophotometrically. Membrane-bound, low-molecular-weight iron is measured on SDS-solubilized ghosts by a ferrozine-based colorimetric test. We adapted these methods for microscale preparation and analysis of erythrocyte ghosts in order to have suitable tools to estimate oxidative membrane damage in human samples. Data from 11 beta-thalassemia intermedia patients and from 10 normal controls are reported as an example of the application of these methods.

Red blood cell antioxidant and iron status in alcoholic and nonalcoholic cirrhosis.

BACKGROUND: Iron overload has been reported in alcoholic liver cirrhosis but it remains to be established whether iron is involved in inducing oxidative damage to erythrocytes in alcoholic cirrhosis. The aim of this study was to assess oxidative damage and red cell indicators of antioxidant defences in alcoholics with mild-to-severe liver cirrhosis, taking into account the iron status. MATERIALS AND METHODS: Twenty-nine patients with alcoholic liver cirrhosis (AC) and 27 with nonalcoholic cirrhosis (NAC) were studied. Serum lipid peroxides (LPO) were assayed by a colourimetric method. Serum-free malonyldialdehyde (MDA) was assayed by selected ion monitoring in positive chemical ionization; serum 4-hydroxy-2(E)-nonenal (4-HNE) was determined by a colorimetric method. Reduced (GSH) and oxidized glutathione (GSSG), adenine and pyridine cofactors were assayed in whole blood extracts by HPLC. Hexose-monophosphate shunt (HMPS), glycolytic pathway (EMP) and antioxidant enzyme activities were determined by standard methods. Iron status was evaluated by standard clinical chemistry and by histological grading of liver iron. Nontransferrin-bound iron (NTBI) was measured in serum by HPLC. RESULTS: GSH progressively decreased with increasing severity of liver involvement in AC and NAC. MDA, 4-HNE and NTBI were significantly higher in AC serum. Stimulation of red cell HMPS and reducing potential, in terms of NADPH production, were more pronounced in AC. CONCLUSIONS: These results suggest that NTBI is more important than the decrease of antioxidant defences in inducing lipid peroxidation. NTBI may play a catalytic role in free radical reactions in the presence of cellular reductants such as NADPH.

Alternative splicing of human G6PD messenger RNA in K562 cells but not in cultured erythroblasts.

The biochemical properties of glucose-6-phosphate dehydrogenase (G6PD) vary in different tissues, and different protein isoforms of the enzyme have been described. Alternative splicing of G6PD intron VII has been detected in transformed lymphoblasts, granulocytes and spermatocytes; the function of this mRNA species is still unknown. We developed a PCR for detecting alternatively spliced G6PD mRNA in K562 and in erythroblasts at different stage of maturation obtained from human peripheral BFU-E in order to evaluate a possible physiological role during erythroid maturation. Trace events of alternative splicing of G6PD intron VII sequences were observed in K562 cells but not in BFU-E-derived erythroid precursors; we consider this phenomenon a non-functional activity in the cells analysed.

Molecular characterisation of an Italian G6PD variant responsible for chronic non-spherocytic haemolytic anaemia.

An Italian deficient G6PD variant associated with chronic non-spherocytic haemolytic anaemia (CNSHA) was biochemically characterised and studied at molecular level. Single-strand conformation polymorphism (SSCP) analysis led to the identification of an abnormal migration pattern of an amplified fragment encompassing exons 10 and 11 of the G6PD gene. Sequence analysis of both strands using an automated fluorescent DNA sequencer revealed a G-->A transition at nt. position 1246 in exon 10. A C-->T substitution at nt. 1311 in exon 11 was also found, which has already been described as a silent mutation common in Caucasians. The 1246 G-->A mutation has been described only in a Japanese subject with CNSHA (G6PD Tokyo) not associated with the 1311T polymorphism, suggesting that this mutation may have arisen independently in Europe and Asia.

G6PD Ferrara I has the same two mutations as G6PD A(-) but a distinct biochemical phenotype.

The cloning and sequencing of the normal glucose-6-phosphate dehydrogenase (G6PD) gene has led to the study of the molecular defects that determine enzymatic variants. In this paper, we describe the mutations responsible for the Ferrara I variant in an Italian man with a family history of favism, from the Po delta. Nucleotide sequencing of this variant showed a G-->A mutation at nucleotide 202 in exon IV causing a Val-->Met amino acid exchange, and a second A-->G mutation at nucleotide 376 in exon V causing an Asn-->Asp amino acid substitution. Although on the basis of its biochemical properties this variant was classified as G6PD Ferrara I, it has the same two mutations as G6PD A(-), which is common in American and African blacks, and as the sporadic Italian G6PD Matera. The mutation at nucleotide 202 was confirmed by NlaIII digestion of a polymerase chain reaction amplified DNA fragment spanning 109 bp of exon IV. The 109-bp mutated amplified sequence is not distinguishable from the normal sequence in single strand conformation polymorphism analysis.

Metabolic indicators of oxidative stress correlate with haemichrome attachment to membrane, band 3 aggregation and erythrophagocytosis in beta-thalassaemia intermedia.

Haematological data, genotype, transfusion requirements, metabolic indicators of oxidative stress (flux via hexose-monophosphate shunt (HMPS); steady state level of GSH and GSSG, NADPH and NADP; activity of anti-oxidant enzymes), parameters of membrane damage (aggregated band 3; membrane-bound haemichromes, autologous immunoglobulins (Igs) and C3 complement fragments) and erythrophagocytosis were measured in erythrocytes (RBC) of 15 beta-thalassaemia intermedia patients (nine splenectomized) with low, if any, transfusion requirements. Patients presented increased aggregated band 3, bound haemichromes, Igs and C3 complement fragments, and increased erythrophagocytosis. Bound haemichromes strongly correlated with aggregated band 3. Anti-band 3 Igs were predominantly associated with aggregated band 3. Erythrophagocytosis positively correlated with aggregated band 3, haemichromes and Igs, suggesting the involvement of haemichrome-induced band 3 aggregation in phagocytic removal of beta-thalassaemic RBC. Splenectomized patients showed higher degrees of membrane damage and phagocytosis, significantly higher numbers of circulating RBC precursors, and tendentially higher numbers of reticulocytes. Basal flux via HMPS was increased twofold, but HMPS stimulation by methylene blue was decreased, as was the glucose flux via HMPS. GSH was remarkably decreased, whereas NADPH was increased. Except for unchanged catalase and glutathione reductase, anti-oxidant enzymes had increased activity. Negative correlation between HMPS stimulation by methylene blue and bound haemichromes indicated that the ability to enhance HMPS may counteract haemichrome precipitation and limit consequent membrane damage leading to erythrophagocytosis.

Biochemical and molecular characterization of a new sporadic glucose-6-phosphate dehydrogenase variant described in Italy: G6PD Modena.

A new glucose-6-phosphate dehydrogenase variant detected in an Italian man from the Po delta is described and designated as G6PD Modena. Biochemical characterization of the variant enzyme revealed an activity 21% of normal, a slow electrophoretic mobility, increased Km value for NADP, decreased Km value for G6P and a complete absence of NADPH inhibition, which could account for the apparently nonhaemolytic feature of this variant. The cloning and sequencing of the G6PD Modena allele showed a G-->C transition at nucleotide 844 in exon VIII causing a Asp-->His amino acid substitution. On the basis of biochemical characterization, G6PD Modena is classified as a genuine variant but it has the same mutation as G6PD Seattle-like.

TT virus infection in adult beta-thalassemia major patients.

BACKGROUND AND OBJECTIVES: Patients with thalassemia-major are at risk of blood-borne viral infections. TT virus (TTV), a single stranded, circular DNA virus, has recently been found to be associated with acute and chronic hepatitis. The aims of this study were to assess the prevalence of TTV infection in adult patients with transfusion-dependent thalassemia, and to evaluate the clinical significance of TTV. DESIGN AND METHODS: We studied 68 adult patients with thalassemia major, 97% of whom were hepatitis C virus (HCV) antibody positive. TTV DNA was amplified from serum by heminested polymerase chain reaction (PCR). Direct sequencing of PCR products was used to establish TTV genotypes. RESULTS: TTV DNA was detected in 47 patients (69.1%). Sequence analysis of PCR products identified TTV genotype 1b as the most common viral genotype in this group. Patients co-infected by HCV and TTV had a significantly higher histologic grade score than patients with isolated HCV infection (5.1+/-2.7 vs. 2.8+/-1.7, p=0.02) while the stage score was not significantly different. INTERPRETATION AND CONCLUSIONS: TTV is highly prevalent among Italian multiply transfused patients. In these patients TTV viremia appears to affect the necro-inflammatory activity of hepatitis C, though no evidence of an effect on the evolution of fibrosis was found.

Hyperferritinemia, iron overload, and multiple metabolic alterations identify patients at risk for nonalcoholic steatohepatitis.

OBJECTIVE: The aim of this study was to define in patients with hyperferritinemia and normal transferrin saturation the relationships among hyperferritinemia, iron overload, HFE gene mutations, the presence of metabolic alterations, and nonalcoholic steatohepatitis (NASH). METHODS: Forty patients with increased serum ferritin, resistant to dietary restriction and normal transferrin saturation, 90 with ultrasonographic evidence of hepatic steatosis, and 60 obligate heterozygotes for hemochromatosis, all negative for alcohol abuse, hepatitis virus infections, and inflammation were studied. Transferrin saturation, serum ferritin, uric acid, lipids, glucose tolerance, insulin resistance, HFE gene mutations, liver histology, and hepatic iron concentration were analyzed. RESULTS: Of the 40 patients with hyperferritinemia, 29 (72%) had biochemical metabolic abnormalities, 18 of the 26 examined (69%) had insulin resistance, 26 (65%) had the presence of one of the two HFE gene mutations (normal controls, 33 of 128 [26%], p < 0.0001), and all had increased liver iron concentration. Thirty-one patients (77%) had histology compatible with NASH. At univariate analysis, NASH was significantly associated with the presence of metabolic alterations, the C282Y mutation, and severity of fibrosis. At multivariate analysis, NASH was associated with the coexistence of multiple metabolic alterations (odds ratio = 5.2, 95% CI = 0.95-28.7). The risk of having NASH augmented in the presence of higher values of ferritin and liver iron concentration. Among the 90 patients with ultrasonographic evidence of hepatic steatosis, 24 (27%) had increased serum ferritin with normal transferrin saturation, but only six remained hyperferritinemic after dietary restriction. CONCLUSION: Increased ferritin with normal transferrin saturation is frequently found in patients with hepatic steatosis, but it reflects iron overload only in those patients in whom it persists despite an appropriate diet. The simultaneous disorder of iron and glucose and/or lipid metabolism, in most of the cases associated with insulin resistance, is responsible for persistent hyperferritinemia and identifies patients at risk for NASH.

Mutations in the HFE gene and their interaction with exogenous risk factors in hepatocellular carcinoma.

The possible role of iron in facilitating the development of liver cancer is still debated. The aims of this study were to define the prevalence of the mutations 845G --> A and 187C --> G (C282Y and H63D) in the HFE gene associated with hereditary hemochromatosis in Italian patients with hepatocellular carcinoma occurring in cirrhosis and to analyze the interaction between these mutations and other established risk factors for hepatocellular carcinoma. The HFE gene mutations, performed by polymerase chain reaction, were analyzed in 81 patients (63 males, 18 females) with hepatocellular carcinoma. None of the patients had a phenotype compatible with homozygous hereditary hemochromatosis. Interaction between HFE mutations and exogenous risk factors was analyzed by collecting information on alcohol consumption, hepatitis B and C virus infections, and iron status at the time of diagnosis of chronic liver disease. This analysis was performed only in males to rule out gender influence on patients' iron status by using the case-only approach specifically designed to estimate departure from multiplicative risk ratios under the assumption of independence between genotype and environmental exposure. The prevalence of the C282Y mutation was significantly higher in patients with hepatocellular carcinoma than in normal controls (8.6% vs 1.6%, P < 0.03). At univariate analysis, iron overload was significantly associated with both HFE mutations (P < 0.0001), whereas ongoing hepatitis B virus infection was associated with the C282Y mutation (P < 0.05). By multivariate analysis, a trend for an increased risk of being positive for hepatitis virus markers (OR 2.9, CI 95% 0.9-9.5) and of having been alcohol abusers (OR 3, CI 95% 0.7-14) was observed in patients heterozygous for the HFE mutations. These data indicate that the prevalence of the main mutation associated with hereditary hemochromatosis is significantly higher in cirrhotic Italian patients with hepatocellular carcinoma compared to a normal population and suggest that heterozygotes for HFE mutations exposed to hepatitis virus infections or who had been alcohol abusers could have an increased risk of developing cirrhosis and later liver cancer than people without the mutations exposed to the same risk factors.