L. Perseu

Cholelithiasis and Gilbert's syndrome in homozygous β-thalassaemia

Cholelithiasis has been reported with a variable incidence in homozygous β‐thalassaemia, the reasons for which have only partially been defined. Disease‐associated factors or specific modifier genes may be implicated. We assessed the prevalence of cholelithiasis and the effect of co‐inherited Gilberts syndrome genotype on its development in 261 thalassaemia major (TM) and 35 thalassaemia intermedia (TI) patients. Cholelithiasis was found in 20·3% of TM and in 57·1% of TI patients. Its incidence was higher (P < 0·05) in patients homozygous for the (TA7) motif in the promoter of the UGT1‐A1 gene, the genotype associated with Gilberts syndrome, which seems to be a risk factor for the development of gallstones in TM and TI patients.

Hyperbilirubinaemia in heterozygous β‐thalassaemia is related to co‐inherited Gilbert's syndrome

The reasons why heterozygotes for β‐thalassaemia have considerable variation in serum bilirubin levels are unkown. High levels of bilirubin could be related to the co‐inherited Gilberts 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 β‐thalassaemia heterozygotes for codon 39 (CAG → TAG) nonsense mutation. 21 normal individuals and 32 unrelated patients with Gilberts syndrome served as controls. The coding sequence region of the UGT‐1A was normal. Five β‐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 Gilberts syndrome, had higher bilirubin levels compared to those with the (TA)6/(TA)7 or (TA)6/(TA)6 configurations.

Hyperbilirubinemia, glucose-6-phosphate-dehydrogenase deficiency and Gilbert's syndrome.

Abstract The pathogenesis of neonatal hyperbilirubinemia has not yet been completely defined in normal and glucose-6-phosphate-dehydrogenase (G6PD)-deficient newborns. The recent identification of a variant promoter in the gene encoding for the bilirubin uridine-diphosphoglucuronosyl-transferase (UGT-1 A) associated with Gilberts syndrome, allowed us to explore whether the presence of this variant promoter is a risk factor for the development of neonatal hyperbilirubinemia in normal newborns and in association with G6PD deficiency. We found that the variant (TA)7/(TA)7 promoter shows no statistically significant difference in normal or G6PD-deficient newborns developing severe hyperbilirubinemia and in control subjects from the same population. This finding indicates that the variant promoter of UGT-1 A does not contribute to the development of hyperbilirubinemia in the newborn.

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 (‐ ‐/‐α) and 36 (14%) patients had the non‐deletional type (‐ ‐/αNDα). 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 μg/l and in adults, was 192 ± 180 μg/l in females and 363 ± 303 μg/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.

Normal individuals with high Hb A2 levels

Summary. Increased haemoglobin (Hb) A2 levels associated with reduced mean corpuscular volume (MCV) and Hb content per cell (MCH) are the most typical features of heterozygous β thalassaemia. However, double heterozygotes for α and β thalassaemia may have normal MCV and MCH but Hb A2 always in the carrier range. In this report we describe two Sardinian families who have increased Hb A2 levels, normal red blood cell indices and normal globin chain synthesis and in whom DNA sequence analysis of β and δ globin genes did not reveal any abnormality. Our findings demonstrate the existence of a genetic trait not resulting from a defect of the β globin gene cluster, transmitted in a dominant manner and manifested as isolated increase of Hb A2.

Molecular characterization of a normal Hb A2β‐thalassaemia determinant in a Sardinian family

In this study we have carried out haplotype analysis at the β‐globin gene cluster and defined the β‐thalassaemia mutations in a large Sardinian family, ascertained through a proband with thalassaemia major, in which several members were carriers of a β‐thalassaemia allele characterized by microcytosis, hypochromia and normal Hb A2 levels (type 2 normal Hb A2 heterozygous β‐thalassemia). The proband was a compound heterozygote for the β°‐39 and the β+ IVS‐2, nt 745 mutations and all the β‐thalassaemia heterozygotes with normal Hb A2 showed the β+ IVS‐2, nt 745 mutation, always associated with haplotype VII. Because of the consistent association of a specific β‐thalassaemia mutation and normal Hb A2 levels, we postulate that this β‐thalassaemia chromosome carries a δ gene (δ‐thalassaemia) which is unable to increase the δ‐globin output in response to β‐thalassaemia.

HB Puttelange [P140(HlS)ALAàVAL] in an Italian Man with Polycythemia

Hb Puttelange [beta 140(H18)Ala-->Val] was found in a 51-year-old Italian man who had mild polycythemia. The variant eluted from ion exchange high performance liquid chromatography at a position between Hb A and Hb A2. It comprised approximately 34% of the total hemoglobin, was weakly unstable and exhibited an increased oxygen affinity. Amplification of the beta-globin exons and nucleotide sequencing revealed a heterozygosity for a GCC-->GTC mutation in codon 140 corresponding to an Ala-->Val replacement. This substitution accounts for the altered functional properties, probably by producing indirect perturbation of the 2 3-diphosphoglycerate pocket through the nearby lysine residue at beta 82(EF6).