Red cell pyruvate kinase deficiency in Southern Sardinia.

Pyruvate kinase (PK) deficiency is the most frequent red cell enzymatic defect responsible for hereditary non-spherocytic hemolytic anemia. The clinical picture is quite variable and the reasons of this variability have been only partially clarified. We report the clinical description and the extended molecular analysis in 3 PK deficient patients with clinical phenotype of variable severity. We studied the clinical and hematological aspects of 3 patients and analyzed the following genes: pyruvate kinase-R, glucose-6-phosphate-dehydrogenase, α-globin, uridindiphosphoglucuronil transferase and HFE. One patient (A) with a severe clinical picture resulted homozygote for exon 8 nt994A substitution, the other 2 (brothers) were compound heterozygotes for exon 8 nt994A and exon 11 nt1456T mutation. One of the two brothers with a more severe phenotype coinherited also had G6PD deficiency, while both had microcytosis due to the homozygosity for the non-deletional form of α-thalassemia ATG→ACG substitution at the initiation codon of the alpha2 globin gene. Our results suggest that extended molecular analysis is useful for studying how several interacting gene mutations contribute to the clinical variability of pyruvate kinase deficiency.

Clinical and molecular analysis of haemoglobin H disease in Sardinia: haematological, obstetric and cardiac aspects in patients with different genotypes.

In this study, 251 Sardinian patients (187 adults and 64 children) with haemoglobin (Hb) H disease were evaluated. Two-hundred and sixteen patients (86%) had the deletional type (- -/-alpha) and 36 (14%) patients had the non-deletional type (- -/alpha(ND)alpha). A clear genotype-phenotype correlation was found, with the non-deletional type more severe than the deletional type. Diagnosis of Hb H disease was incidental in about 60% of cases. Aplastic crises due to B19 parvovirus infection were found in five patients (2.1%), while 23 patients (9.6%) experienced one or more haemolytic crises. Nineteen patients with Hb H received sporadic red blood cell transfusions and three patients were repeatedly transfused. Forty-seven of 61 married women (77%) had 82 pregnancies. In children, mean serum ferritin was 87 +/-92 mug/l and in adults, was 192 +/- 180 mug/l in females and 363 +/- 303 mug/l in males. For the 98 male patients, a significant correlation was found between ferritin values and age (r2 = 0.33, P < 0.0001). In the Sardinian population, Hb H disease needs regular monitoring for early detection and treatment of possible complications, such as worsening of anaemia that may require red cell transfusion, cholelithiasis and iron overload.

[Histological picture of liver disease in thalassemia intermedia]. / Quadro istologico dell'epatopatia nella Talassemia intermedia.

Thalassemia Intermedia (TI) is a clinical definition in use for a spectrum of clinical conditions ranging in severity from the asymptomatic carrier status to the transfusion-dependent status. The histological lesions of the liver in patients affected by TI has not seen well characterized yet. The aim of this study was to define the histological picture of liver disease in TI. To this end we studied our pool of 22 Thalassemia Intermedia patients who underwent liver biopsy; none of them had blood transfusion. We took into consideration fibrosis according to Ishak's staging and iron overload according to Sciot's grading. Moreover, we determined the hepatic iron content by atomic absorption spectroscopy. Our results have shown that, in all patients studied, the histological picture was characterized by the increase in liver iron stores. By Perls's stain haemosiderin appeared to be stored mainly in hepatocytes in the majority of cases. Inspite of the large amounts of liver iron in these patients, fibrosis was absent or mild. We also noted the presence of iron-free-foci, in part of the patients. Our data show that the histological and histochemical picture of liver disease in Thalassemia Intermedia is very similar to that found in Thalassemia Major. The finding of iron-free-foci could induce to consider a follow up of these patients, even if asymptomatic.

Co-inherited Gilbert's syndrome: a factor determining hyperbilirubinemia in homozygous beta-thalassemia.

BACKGROUND AND OBJECTIVE: Patients with thalassemia major and intermedia show a marked variability of serum indirect bilirubin levels. In this paper we tested the hypothesis related to the variability of the glucuronidation bilirubin rate which depends on the configuration of the A(TA)nTAA motif of the UGT1*1 glucuronosyltransferase gene promoter. DESIGN AND METHODS: We studied the configuration of the A(TA)nTAA motif in 26 patients with thalassemia major and 34 with thalassemia intermedia. RESULTS: In patients with thalassemia major and in those with thalassemia intermedia significantly higher bilirubin levels were found in patients with the (TA)7/(TA)7 genotype, than in those with the (TA)7/(TA)6 or (TA)6/(TA)6 genotype. INTERPRETATION AND CONCLUSIONS: These results indicate that the (TA)7/(TA)7 genotype, the configuration found in patients with Gilbert's syndrome, is capable of modifying the clinical phenotype of homozygous beta-thalassemia. This is an example of the role played by co-inherited modifying gene(s) on the extent of clinical heterogeneity of monogenic disorders.

Hyperbilirubinaemia in heterozygous beta-thalassaemia is related to co-inherited Gilbert's syndrome.

The reasons why heterozygotes for beta-thalassaemia have considerable variation in serum bilirubin levels are unknown. High levels of bilirubin could be related to the co-inherited Gilbert's syndrome, determined either by mutations of the coding region or by variation in the A(TA)nTAA motif of the promoter of the bilirubin UDP-glucuronosyltransferase gene (UGT-1). We sequenced the coding and the promoter region of UGT-1A or characterized the A(TA)nTAA motif of the promoter by denaturing gel electrophoresis of radioactive amplified products. The results were correlated with bilirubin levels in 49 beta-thalassaemia heterozygotes for codon 39 (CAG --> TAG) nonsense mutation. 21 normal individuals and 32 unrelated patients with Gilbert's syndrome served as controls. The coding sequence region of the UGT-1A was normal. Five beta-thalassaemia heterozygotes, who were homozygous for the extra (TA) bases in the A(TA)nTAA element of the promoter of UGT-1A, the configuration present in homozygosity in Gilbert's syndrome, had higher bilirubin levels compared to those with the (TA)6/(TA)7 or (TA)6/(TA)6 configurations. In the group of 32 patients with Gilbert's syndrome, 31 of whom had the (TA)7/(TA)7 configuration, we detected 14 heterozygotes for beta-thalassaemia, a figure much higher than predicted on the basis of the carrier rate. Homozygosity for the (TA)7 motif, the typical promoter configuration of Gilbert's syndrome, is one of the factors determining hyperbilirubinaemia in heterozygous beta-thalassaemia.

Serum erythropoietin and erythropoiesis in high- and low-fetal hemoglobin beta-thalassemia intermedia patients.

Clinical data suggest that in beta-thalassemia-intermedia patients, higher levels of circulating fetal hemoglobin (HbF) are associated with greater disease severity at comparable degrees of anemia. We assessed the influence of the amount of circulating HbF on serum erythropoietin (s-Epo) levels and on serum transferrin receptor, a measure of erythropoiesis, in 30 beta-thalassemia-intermedia patients. Twenty-four showed more than 40% HbF (21 of whom with beta (0)-thalassemia) and 6 presented lower HbF levels (beta(+)-thalassemia). The two groups of patients did not differ in age (15.3 v 19 years, respectively) or degree of anemia (Hb = 8.8 g/dL in both groups). Log (s-Epo) was correlated inversely with Hb (r = -0.47; P < .01), and directly with HbF (r = .55; P < .001). Multivariate regression analysis showed that Hb and HbF were independently correlated with s-Epo levels. High-HbF patients had greater s-Epo values at the same Hb level than low-HbF patients. Considering that iron-deficiency anemia control patients represented the predicted physiologic response of s-Epo to anemia, the observed/predicted s-Epo ratio in low-HbF thalassemic patients was no different from controls, but was increased in the high-HbF group. High-HbF patients also showed an expansion of erythropoiesis as much as four to nine times the normal value at the same Hb level as low-HbF patients. We conclude that HbF exerts an independent regulatory effect on erythropoietin production and erythropoiesis that is detectable only when HbF levels exceed 40%.

HbH disease in Sardinia: molecular, hematological and clinical aspects.

In this study we have defined the molecular basis and correlated the clinical phenotype with the alpha-globin genotype in a large series of patients of Sardinian descent with HbH disease. The most prevalent molecular defect was the deletion of 3 alpha-globin structural genes most commonly the (--/-alpha 3.7) genotype (83.6%) and rarely the (--/-alpha 4.2) genotype (1.4%), followed in decreasing order of incidence by the combination of deletion alpha zero-thalassemia and initiation codon mutation of the alpha 2-gene (--/alpha NcoI alpha = 9.8%), deletion alpha zero-thalassemia and pentanucleotide deletion of IVS-I of the alpha 2-globin gene, (--/alpha HphI alpha = 3.3%) deletion alpha zero-thalassemia and initiation codon mutation of the alpha 1-gene (--/alpha alpha NcoI = 1.3%), a homozygous state for initiation codon mutation of the alpha 2-gene (alpha Nco alpha/alpha NcoI alpha = 0.7%). Patients with the (--/alpha thal alpha) genotypes showed severer clinical and hematological features as compared to those with the (--/-alpha) or those with the (--/alpha alpha thal) genotypes. The single patient with the (alpha Nco alpha/alpha Nco alpha) genotype had a clinical phenotype intermediate between HbH disease and the alpha-thalassemia carrier status. This heterogeneity depends on the fact that the alpha 2-globin gene produces 2-3 times alpha-globin chains than the alpha 1-gene and the single remaining alpha 1-like globin gene in the -alpha 3.7 chromosome has a compensatory increase in the alpha-globin chain output. alpha-Globin gene mapping of HbH disease patients may be useful for predicting the clinical outcome and to improve genetic counseling.

Iron stores and iron deficiency anemia in children heterozygous for beta-thalassemia.

This paper describes the status of iron stores, the incidence and the hematological characteristics of iron deficiency anemia in children heterozygous for beta-thalassemia. In beta-thalassemia heterozygotes, iron stores were similar to the controls in infancy and tended to increase with age, reaching levels of moderate iron overload solely in adult males. Iron deficiency anemia occurred less frequently in children heterozygous for beta-thalassemia as compared to normal controls, while no difference between the two groups was observed in the incidence of iron deficiency. Ineffective erythropoiesis, typical of heterozygous beta-thalassemia, by causing an increase of iron absorption may limit the effect of iron shortage. At similar levels of iron depletion, however, children heterozygous for beta-thalassemia develop a more severe anemia as compared to non beta-thalassemic children. With the exception of two children, HbA2 levels in the presence of iron deficiency anemia remain in the range of heterozygous beta-thalassemia. In conclusion, our results indicate that children heterozygous for beta-thalassemia have normal iron stores but are relatively protected against the development of iron deficiency. When iron deficiency anemia develops, its clinical expression is usually more severe than in non beta-thalassemic children.

Molecular analysis of beta zero-thalassemia intermedia in Sardinia.

In this study we have carried out alpha- and beta-globin gene analysis and defined the beta-globin gene polymorphisms in a group of patients with thalassemia intermedia of Sardinian descent. A group of patients (109) with thalassemia major of the same origin served as control. Characterization of the beta-thalassemia mutation showed either a frameshift mutation at codon 6 or a codon 39 nonsense mutation. We found that homozygotes for the frameshift mutation at codon 6 or compound heterozygotes for this mutation and for the codon 39 nonsense mutation develop thalassemia intermedia more frequently than thalassemia major. The frameshift mutation at codon 6 was associated with haplotype IX that contains the C-T change at position -158 5' to the G gamma globin gene implicated in high gamma chain production and thus the mild phenotype. In patients' homozygotes for codon 39 nonsense mutation, those with thalassemia intermedia more frequently had the two-gene deletion form of alpha-thalassemia, or functional loss of the alpha 2 gene as compared with those with thalassemia major. In a few siblings with thalassemia major and intermedia, the thalassemia intermedia syndrome correlated with the presence of the -alpha/-alpha genotype. No cause for the mild phenotype was detected in the majority of patients who had not inherited either haplotype IX or alpha-thalassemia.

Molecular mechanism accounting for milder types of thalassemia major.

We carried out alpha-globin gene analysis by restriction endonuclease mapping in 91 Sardinians with homozygous transfusion-dependent beta 0-thalassemia and correlated the clinical findings with the alpha-globin genotype. In patients (n = 6) with deletion of two alpha-globin structural genes, disease onset and transfusion dependence occur later than in those (n = 50) with a full complement of alpha-globin genes. There was no statistically significant difference in the group of patients (n = 35) with deletion of only one alpha-globin gene. Patients with deletion of two alpha-globin genes had significantly higher Hb A2 levels than those with a full complement of alpha-structural genes and those with deletion of a single alpha-globin gene. From this and other studies, it seems that the deletion of two alpha-globin structural genes may convert the common severe clinical picture associated with homozygous beta 0-thalassemia to milder forms, ranging from a later occurring but still transfusion-dependent type to a non-transfusion-dependent form.