Hb F Kingston (G gamma 55 (D6) Met leads to Arg)

A fetal haemoglobin variant was noted in a healthy Jamaican infant of mixed African/Chinese extration. A two-dimensional chromatogram of the soluble tryptic peptides (Tp) showed 2 'new' ones. One was composed of the last 4 residues of the usually insoluble Tpgamma41-59. To permit a tryptic split this required a change of residue gamma 55 Met to Lys or Arg. The other new Tp contained arginine and was in the position expected for a Ty gamma41-55 (55 Arg). As the material was limited it could not be analysed. When after more than 6 years no example of Hb F Kingston had become available it was decided to describe the variant on the basis of the present evidence. (AU)

Sickle cell-Hb Lepore Boston syndrome: uncommon differential diagnosis to homozygous sickle cell disease

Two siblings assumed on the basis of clinical and hematological evidence to have homozygous sickle cell (SS) disease were found to have a mother without sickle hemoglobin. Subsequent investigation and hemoglobin structural studies indicated the diagnosis to be sickle cell-Hb Lepore Boston syndrome. This syndrome generally manifests clinically significant sickle cell disease, and this genotype should be borne in mind in apparent SS disease where a parent without sickle hemoglobin is discovered.(AU)

The measurement of glycosylated haemoglobins by the cation exchange chromatographic method in subjects with abnormal haemoglobins

Glycosylated haemoglobins were estimated in subjects with normal and abnormal haemoglobins by a cation exchange chromatographic method. Lower values were obtained in the subjects with abnormal haemoglobins. Diabetic subjects tend to have higher values. In interpreting the values in subjects with abnormal haemoglobins either different reference ranges must be used or a correction factor can be employed (AU)

Mapping of antigenic sites on human haemoglobin by means of monoclonal antibodies and haemoglobin variants

Monoclonal antibodies specific for human globin chains have been prepared and the following strategy has been applied in delimiting the antigenic sites involved in antibody binding. The structural sites of the human globin subunit that might be recognised by the monoclonal antibody were deduced from comparisons of the primary structures of mamalian globin chains that did or did not react with the antibody. The involvement of individual residues at these specific sites was subsequently tested by reacting the antibody with abnormal human haemoglobins in which there was either a substitution or a structural site recognised by monoclonal antibody HuHb á 3-2 (an antibody that reacts with the adult haemoglobins from man and macaque monkey, but not with those from baboon and mouse) includes the aspartic acid residue at position 52 of the á-globin subunit.(AU)

Haematological factors associated with proliferative retinopathy in homozygous sickle cell disease

Haematological indices were investigated in 261 patients with homozygous sickle cell disease, 29 of whom had developed proliferative sickle retinopathy (PSR). After allowing for age-related effects, male patients with high Hb (>9 g/dl) and low HbF (<5 ) percent levels appeared to constitute a high risk group for PSR. This relationaship was not evident in females, PSR being observed in patients with lower Hb and higher HbF levels than in the male group. PSR occurred in 14 percent of patients aged 40 years or over in this sample (AU)

Detection of alpha thalassaemia in Negro infants

A prospective study of 2191 Negro infants in Jamaica showed that approximately 7 percent of them had detectable levels of Hb Bart's (Y4) in the neonatal period. The red cell indices, globin chain biosynthesis and restriction endonuclease mapping of DNA from these infants were used to determine the significance of Hb Bart's at birth. The results indicate that the genotypes OO/OO, - O/OO and - O/-O are associated with 0 percent, 0.1-2 percent, and greater than 2 percent Hb Bart's respectively. Although trace amounts of Hb Bart's may be associated with the genotype - O/OO this is not always the case and therefore haemoglobin analysis in the neonatal period cannot be used to diagnose this genotype with any certainty (AU)

Abnormal hemoglobins in Surinam: I. frequency among the different ethnic groups

In this paper, after a review of the literature dealing with abnormal hemoglobins in Surinam, two research projects on this genetic disorder are described. First, the results are given of a project screening the three major ethnic groups: Negroes, East-indians and Javanese. Second, the preliminary results of a survey among women attending the Government hospitals for delivery are mentioned. Also the results on a number of babies are presented.The sickle cell gene is the most frequent one in the negroid groups and is also found in all other groups. Other abnormal hemoglobins encountered are HbC, which is so far only demonstrated in the negroid groups, and HbE, present in every group, but mainly in Javanese.(AU)

Beta-chain variants in Jamaica newborns

In an electrophoretic study of 15,661 Jamaican cord bloods, 8 rare beta-chain variants were found in 18 subjects in addition to the common beta-chain variants, Hb S and Hb C. The heterozygote frequencies for Hb S and Hb C were 10.1 percent and 3.7 percent respectively. The most frequent of the rare beta-chain variants were Hb Korle Bu (beta 73 Asp leads to Asn) (7 cases) and Hb O su-Christiansborg (beta 52 Asp leads to Asn) (3 cases). One new beta-chain variant, Hb Caribbean (beta 91 Leu leads to Arg) was found. (AU)

Use of blood specimens collected on filter paper in screening for abnormal hemoglobins

Both cellulose acetate electrophoresis and citrate agar electrophoresis were performed on 834 blood samples collected on filter paper in Jamaica and shipped for testing to the National Hemoglobinopathy Standardization Laboratory at the U.S. National Center for Disease Control. Additionally, 30 blood samples collected locally were stored on filter paper, in microhematocrit capillary tubes, and as whole blood specimens; at selected times the samples were tested for stability to determine the best sample-collection technique for hemoglobin electrophoresis. Results were most nearly accurate when both cellulose acetate electrophoresis and citrate agar testing were used. The methods are easy to perform, but results are unreliable if the blood samples on filter paper are stored at 4§C for longer than two weeks before they are tested (AU)

Haemoglobin Spanish Town alpha27 Glu replaced by Val (B8)

A new alpha chain variant Hb Spanish Town, a27 Glutamic acid-Valine, awas detected in the cord blood of a Jamaica Negro infant. In the mother the adult component (a2 Spanish TownB2) has an electrophoretic mobility between haemoglobins S and F at alkaline pH and measures 11.0-12.0 percent of the total haemoglobin. (Summary)

Linkage relationships between beta- and delta-structural loci and African forms of beta thalassaemia

Five families are described in which there have been matings between individuals doubly heterozygous for beta thalassaemia and the delta-chain variant haemoglobin A2' to normal persons. In all there were 24 informative offspring. There were no crossovers between the beta-thalassaemia and delta-chain loci; in three of the families the genes were linked in cis and in two families the genes were found in trans.Together with previously reported families there have now been 58 opportunities for crossing over between the beta-thalassaemia and delta-chain loci and there have been two possible and one highly probable crossovers. Of the total of 9 families reported to date 4 have had the genes for beta thalassaemia and Hb A2' in cis and 5 in trans. These findings are contrasted with the findings in families where a beta-chain structural variant and Hb A2' have been observed together and these genes have always been found in trans and never in cis. The reasons for linkage disequilibrium of this type are discussed. It is concluded tentatively that the distance between the delta-structural and beta-thalassaemia loci is greater than that between the delta-structural and beta-structural loci. To date this conclusion can only be applied to the beta+ -thalassaemia and beta-thalassaemia genes as found in the African population, since this is the only population with a high incidence of delta-chain mutants which allow linkage analysis of this type to be carried out. (AU)

Gamma chain variants in Jamaica newborns

15,661 cord bloods from Jamaican infants were examined for abnormal hemoglobins using alkaline cellulose acetate electrophoresis for the initial screening, supplemented by acid agar gel electrophoresis for samples exhibiting abnormal hemoglobin bands. Of the 16 electrophoretic variants which were detected, six were fully characterized and found to be: four Hb F Port Royal (alpha2 Ggamma2 125 Glu replaced by Ala) and two Hb F Victoria Jubilee (alpha2Agamma2 80 Asp replaced by Tyr). The Hb F Port Royal samples each constituted about one eighth of the total Hb F as did seven additional samples presumed to be Hb F Port Royal. The infants with this variant exhibited no special hematological characteristics or other consistent associations. Both Hb F Victoria Jubilee samples ocurred in somewhat lower proportions of the total Hb F compared with Hb F Port Royal and exhibited an apparent increase of free alpha chains in the whole hemolysate. The data available on detectable gamma chain variants suggest that a specific point mutation may occur in either a HbGgamma or a HbAgamma locus. (AU)

Hemoglobin F Port Royal (alpha2G gamma2 125 GLU leads to Ala)

A Gy-chain variant, Hb F Port Royal, with an electrophoretic mobility intermediate between Hb S and Hb C was found in a Jamaican-Negro infant, and made up to 14-15 percent of the total Hb F. A glycinamidation procedure was employed to aid in the determining the amino-acid residu substitution of gamma 123 Glu leads to Ala, and the presence of glycine in position 136. (AU)

The prevalence of the rarer inherited haemoglobin defects in adult Jamaicans

The prevalence of several haemoglobin defects, including the traits for á-thalassaemia (0.8 percent), hereditary persistence of foetal haemoglobin (0.2 percent) and the abnormal delta change haemoglobin, Hb B2 (2.4 percent), were determined from the combined results of surveys conducted on adults in a suburban and a rural community. Mean Hb A2 levels of 2.6 ñ0.4 percent, 5.3 ñ0.5 percent and 2.0 ñ0.2 percent were found in 639 Hb A homozygotes, seven á-thalassaemia traits and three traits for hereditary persistence of of foetal haemoglobin (HPFH), respectively. Levels of alkali resistence haemoglobin (A.R.Hb) ranged from 0.6 to 7.3 percent in the thalassaemia traits and were 21.0, 19.0 and 16.0 percent in the three HPFH traits; the remaining 770 subjects in whom A.R.Hb was measured had a mean value of 0.6 ñ0.6 percent. (AU)