L. Tentori

Haemoglobin Lepore trait: haematological and structural studies on the Italian population.

Summary. Haematological data on 59 heterozygotes for haemoglobin (Hb) Lepore and 10 double heterozygotes for Hb Lepore and β thalassaemia from 36 Italian families are reported. The red cell indices are defined and compared with those of groups of non‐thalassaemic and β thalassaemic subjects of comparable number, age and sex distribution. The relative level of each haemoglobin fraction and the absolute production of single polypeptide chains are calculated in order to compare the expression of the non‐α chain genes in Hb Lepore trait and β thalassaemia. Structural studies demonstrate that the haemoglobin Lepore is of the Boston type (δ87β116) in all subjects, confirming that this type of fusion variant is probably the only one which occurs in Mediterranean populations. The distribution and incidence of the Lepore haemoglobinopathy are discussed.

A new abnormal human hemoglobin: Hb prato (α231 (B12) Arg→Ser β2)

Abstract An abnormal human hemoglobin was found in a hemolysate from a 5-year-old healthy child living in Prato (Tuscany, Italy). Structural studies demonstrated a previously unreported amino acid substitution, α31 (B12) Arg → Ser (this is an α 1β1 contact). The new variant has been named Hb Prato. It was unstable in isopropanol and heat-denaturation tests, but has normal functional properties, with respect to whole blood studies. Family studies indicated that the variant had been inherited from the mother, a 39-year-old woman of Sicilian extraction. Hb Prato occurs at 20 and 28% in hemolysates from the boy and woman, respectively.

Hemoglobin Maputo : A New 6-Chain Variant (α2β2 47 (Cd6) Asp→Tyr) in Combination with Hemoglobin S, Identified by High Performance Liquid Chromatography (Hplc)

During a routine hematological investigation, a slowly-moving hemoglobin variant was detected in a 2-year-old child from Maputo (Mozambique) in combination with hemoglobin S. Structural studies carried out by HPLC demonstrated a previously unreported amino acid substitution, β 47 (CD6) Asp→Tyr. The new hemoglobin variant has been named hemoglobin Maputo.

Molecular heterogeneity of beta thalassaemia in the Italian population

Summary Fifty‐one subjects originating from Southern Italy and affected by Cooleys anaemia have been studied in order to define the degree of heterogeneity of β thalassaemia mutations in this high incidence area. Restriction endonuclease mapping has been carried out on genomic DNA by the Southern blot technique both to exclude the existence of gross deletions or rearrangements and to establish the relative frequency of four polymorphic restriction sites (i.e. Gγ and Aγ Hind III, β Ava II and β Bam HI) within the γδβ gene region. In 28 subjects unequivocal linkage of the four polymorphic sites has been determined leading to the identification of seven different chromosome haplotypes, six of which had previously been reported associated with specific β0 and β+ thalassaemia mutations. Globin chain synthesis studies on peripheral blood reticulocytes indicated that subjects carrying the same genotype may behave differently as far as the β chain production is concerned relative to both the a and the non‐α chains. Thus, β thalassaemia turns out to be quite heterogeneous even in this limited geographical area. β+ mutations appear to be predominant, particularly those affecting nuclear precursor RNA splicing to mature β globin mRNA.

Hemoglobin bologna (α2β2 61 (E5) Lys → Met) An abnormal human hemoglobin wlth low oxygen affinity

Abstract An abnormal human hemoglobin was found in association with β-thalassemia in a hemolysate from an 11-year-old healthy child living in Bologna (northern) Italy). Structural studies demonstrated a previously unreported amino acid substitution, β 61 (E5) Lys → Met (this is an external residue). The new variant has been named Hb Bologna, and is characterized by a reduced oxygen affinity. Family studies indicated that the variant had been inherited from the father, a 41-year-old male of Southern Italian origin. Also, a brother of the propositus was found to be an abnormal Hb carrier.

Post-translational control of human hemoglobin synthesis The role of the differential affinity between globin chains in the control of mutated globin gene expression

The interactions between beta-thalassemia and the human hemoglobin (Hb) alpha-chain variants, Hb Hasharon, Hb O Idonesia and Hb J Paris, and between alpha-thalassemia and the beta-chain variants, Hb S, Hb C and Hb G San José, which are characterized by preferential decrease of the abnormal Hb level in peripheral bloods, have been studied. Both biosynthesis studies in reticulocytes and determination of the relative affinity of abnormal chains for normal complementary chains by in vivo recombination experiments, involving globin chains previously isolated in their native form, have been carried out in order to provide insights on the molecular events following the synthesis of the mutant chains under conditions of complementary chain deficiency. Furthermore, we have measured the relative affinity for complementary chain of beta D Los Angeles- and alpha J Rovigo-chains, the level of which does not decay in thalassemic carriers, and of alpha Legnano- and beta Osu Christiansborg-chains, which have not yet been observed in association with thalassemias. Our experiments indicated that the differential affinity for beta-chains is not always the major post-translational control mechanism which regulates the level of certain alpha-chain variants in beta-thalassemic heterozygotes, and that preferential removal of abnormal chains by proteolytic enzymes is likely to play an important role in most cases. On the other hand, the low affinity of certain variant beta-chains for alpha-chains may offer an explanation for the low level of certain beta-chain variants in peripheral blood of non-thalassemic carriers, as well as to their decrease under conditions of relative alpha-chain deficiency (alpha-thalassemias).

Properties of hemoglobin G. Ferrara (β57(E1) Asn → Lys)

Abstract Hemoglobin G. Ferrara is an abnormal human hemoglobin in which an asparagine residue is replaced by a lysyl residue at position β 57 (β 57 Asn → Lys). Oxygen equilibria show that cooperativity and alkaline Bohr effect are maintained to normal levels while the acid Bohr effect appears increased; in addition, a smaller effect of diphosphoglycerate is also observed. Flash photolysis experiments performed as a function of protein concentration show that the fraction of quickly reacting form is always higher than that of human hemoglobin A. This fact, together with the increase of the oxygen affinity observed at acid pH values, may be related to an enhanced dissociation of the molecule into dimers. Several attempts to isolate the native chains by treatment of the protein with p -chloromercuribenzoate were unsuccessful due to the great instability of the isolated variant β-chains, which precipitated completely during incubation with p -chloromercuribenzoate. Therefore, although the substitution is on the surface of the molecule, there are several properties of hemoglobin G. β Ferrara which are clearly different from hemoglobin A.

A new human hemoglobin variant: Hb Bari (α2 45 (CD3) His → Gln β2)

Abstract An α-chain variant hemoglobin was found in the hemolysate of a 21-year-old healthy male living in Bari (Puglia, Italy). Structural studies demonstrated a previously unreported amino acid substitution, α2 45 (CD3) His → Gln β2, involving a distal heme contact. The new variant has been named Hb Bari. Its electrophoretic behavior was the same as for Hb A; it was stable to both isopropanol and heat denaturation and exhibited normal functional properties, with respect to whole blood and stripped hemolysate studies. The level of Hb Bari was about 20% in the observed carrier. No relative was available for further investigations.

Hemoglobin Gavello - α2β2 47(CD6) Asp → Gly a new Hemoglobin Variant from Polesine (Italy)

During a survey for abnormal hemoglobins in Polesine (a region north of the Po river, where betathalassemia is very frequent) a slow moving variant was noted in a 79-yr-old woman living in Gavello, a small town in the province of Rovigo. Structural studies demonstrated a previously undescribed amino acid substitution, 647 Asp a Gly. This new variant has been named Hb Gavello.

Hemoglobin Hasharon [α2 47 (CD5) Asp→ His β2]Linked to α-Thalassemia in Northern Italian Carriers

This report is concerned with the evaluation of hematological parameters and of both relative (%) and absolute (mean pg/cell) quantities of the abnormal Hemoglobin (Hb) Hasharon in 53 heterozygous carriers and 7 double heterozygotes for Hb Hasharon and beta-thalassemia from 43 apparently unrelated families living in the province of Rovigo (northern Italy). Biosynthetic studies are also reported. The data strongly suggest the presence of an alpha-thalassemia-2 determinant closely linked to the alpha Hasharon-chain locus. Selective advantage of heterozygotes carrying such alpha-haplotype would explain the relatively high frequency of Hb Hasharon (0.23%) in northeastern Italy, a past-endemic malaria region. The interaction between Hb Hasharon and beta-thalassemia results in preferential decrease of the abnormal Hb level.