Studies on the Proportion and Synthesis of Haemoglobin G Philadelphia in Red Cells of Heterozygotes, a Homozygote, and a Heterozygote for both Haemoglobin G and α Thalassaemia

SUMMARY. The proportion of Hb G Philadelphia (α68-Asnalys) in heterozygotes has been found to have a well-defined bimodal distribution around means of 33% and 46% Hb G. Microcytosis and hypochromia are consistently associated with the latter group, who also have a decreased ratio of α/β-chain synthesis in the peripheral blood, but these characters are not linked to the Hb-Gα gene, because a parent with microcytosis and 46% Hb Gα may have offspring with 33% Hb G without significant microcytosis. In one family a subject with Hb G and Hb G₂ but no Hb A or Hb A₂ is presumably a homozygote for α^G. This subject has microcytosis and a decreased ratio of α/β chain synthesis. In another family a subject with Hbs H, G and G₂ but without Hbs A or A₂ is heterozygous for both Hb G and α thalassaemia 1. These findings are compatible with the hypothesis that the α^G mutation occurs on a chromosome with only a single αchain locus and that the expression in heterozygotes as 46% or 33% Hb G is determined by the homologous chromosome in trans having either one or two normal α^A genes respectively. The significance of this polymorphism for chromosomes carrying αchain genes is discussed.     

Serological Studies on an α-D-Galactosyl-Binding Lectin Isolated from Bandeiraea simplicifolia Seeds

Abstract. The serological characteristics of a highly purified α-D-galactosyl-binding lectin, isolated from extracts of Bandeiraea simplicifolia seeds, are described. These studies show that the lectin preferentially agglutinates group B red cells and in addition has the capacity to distinguish between group A₁ and group A₂ erythrocytes.
Since the lectin is not absolutely specific for group B red cells, it is therefore unsuitable as an anti-B blood typing reagent. However, the reactions obtained against Tn and 'acquired-B' red cells suggest that it may be of value in the elucidation and classification of red cell polyagglutinable states.     

Assay of α-N-Acetylgalactosaminyltransferases in Human Sera: Further Evidence for Several Types of Am Individuals

Abstract. The study of the α - N -acetylgalactosaminyltransferase in the sera of 19 individuals belonging to the rare A_m blood group makes it possible to confirm the heterogeneity of this phenotype established on genetical and immunological criteria. Two groups of subjects, Am and A_y, can be distinguished.
For the individuals of the first group, named A_m, 15 samples (7 families) have been studied, the phenotype is inherited as an allele at the ABO locus. 14 of these subjects, have an α - N -acetylgalactosaminyltransferase whose kinetic properties were similar to those of A₁ subjects. In one family, however, the A transferase detected is of the A₂ type. On a quantitative level, the enzyme activities of these sera only reached 30–50% of the average value observed for A₁ or A₂ subjects, respectively.
These facts suggest the existence of a genetic inhibitor, possibly linked to the ABO locus, preventing either an A₁ or A₂ gene from acting at the level of some cellular lines and leading therefore to the recognition of phenotypes named A^A₁^m and A^A₂^m
On the contrary, under the experimental conditions used, no α - N -acetylgalactosaminyltransferase activity was detected among the four individuals of the second group, named A_y by W einer et al. [37], and whose appeareance in siblings results from the action of a recessive modifying y^A gene.     

A New Genetic Marker of Human Immunoglobulins Determined by an Allele at the α2 Locus

Abstract. A new antigenic determinant occurring on human IgA2 protein is described. In family studies this marker showed to be dominant, non-sex-linked and antithetical to the first known marker of α2 chains. It is proposed to call this marker A₂m(2), indicating that it is the second marker of IgA2 proteins.     

FIRST DESCRIPTION OF A FRAMESHIFT MUTATION IN THE α1-GLOBIN GENE ASSOCIATED WITH α-THALASSAEMIA

A frameshift mutation in the α₁-globin gene, responsible for a clinically mild α-thalassaemia phenotype, has been characterized in a Spanish woman. After excluding the most common forms of α-thalassaemia found in the Mediterranean area, both α-globin genes (α₁ and α₂) were amplified and analysed selectively by non-radioactive single-strand conformation polymorphism (SSCP). An abnormal SSCP mobility was present in the second exon of the α₁-globin gene and direct sequence analysis revealed a 13 bp deletion (between codons 51 and 55) affecting a single allele. The consequence of this mutation is a reading frameshift leading to a novel amino acid coding sequence from codons 51–61 and a premature stop signal at new position 62, which results in a net reduction of the affected α-globin chain output. The presence of this new mutation was confirmed by restriction enzyme analysis of the specific PCR product.     

Rapid analysis of -α3.7 thalassaemia and αααanti 3.7 triplication by enzymatic amplification analysis

Summary In this report we describe a PCR-based method for the diagnosis of the most common form of α thalassaemia, the –α^3.7 deletion which occurs throughout all tropical and subtropical regions of the world. The same procedure also identifies the reciprocal recombinant chromosome (ααα^{anti 3.7}). Restriction mapping of the PCR products has enabled us to distinguish between the type I (–α^3.7I), type II (–α^3.7II) and type III (–α^3.7III) deletions. This strategy will be very useful in screening programmes of α thalassaemia occurring on its own or in association with β thalassaemia and sickle cell disease.     

Homozygous deletional α+ thalassaemia associated with unequal expression of the two remaining α1 genes (α1A and α1Q)

S ummary . A Cambodian family presenting several haemoglobinopathies, Hb E, Hb Q and α⁺ thalassaemia, has been investigated. DNA analysis showed that the thalassaemia syndrome corresponds to a leftward type (4.2 kb) deletional from of α⁺ thalassaemia. Genotypes found in the family are: propositus -α^A/-α^Q, β^A/β^E, mother and older sister α^Aα^A/ -α^Q, β^A/β^E; father α^Aα^A/-α^A, β^A/β^A. The propositus consistently presents an α^Q/α^A chain ratio of 60/40 although both chains are products of α₁ loci. The relatively higher expression of the α^Q chain is not observed in the mother and therefore makes it unlikely to reflect anything other than differential expression of the maternal -α^Q/ and paternal -α^A/ haplotypes. This observation raises the possibility that both haplotypes are not strictly identical and that the region of the cross-over event is important for α gene expression.     

Antiplasmin Activity of Rat Serum Slow α-Globulins

The antiplasmin activity of serum slow α₁- and α₂-globulins has been studied in rats injected with streptokinase/human serum and human or rat plasmin. Highly significant falls in serum slow α₁ -globulin were noted soon after administration of streptokinase and human or rat plasmin; this suggested a reaction between plasmin and slow α₁-globulin with rapid removal of the resultant complexes. Rats with immune complex nephritis (ICN) given streptokinase showed a highly significant increase in slow α₂-globulin, but no change in slow α₂-globulin was noted following injection of human plasmin. Using fibrin agar plates additional evidence was obtained that rat slow α₁-globulin inhibited digestion of fibrin by plasmin. We conclude that of the two globulins in the rat only slow α₁-globulin shows antiplasmin activity and we believe that this represents the functional analogue of α₁-macroglobulin in the human.     

The Abnormal Haemoglobins in Homozygous α-Thalassaemia

S ummary The red cells from Chinese stillborn infants with erythroblastosis foetalis due to homozygous α-thalassaemia contain about 80% Hb-_γ4, the second haemoglobin always present does not contain α-chains and has the structure Hb_γ2X₂ identical to Hb-Portland 1. Hb-A, Hb-F, or Hb-A₂ were not detected.     

REVIEW: α1-Antitrypsin deficiency associated liver disease

α₁-Antitrypsin (α₁-AT) deficiency is the most common genetic cause of liver disease in children and genetic disease for which children undergo liver transplantation. It also causes cirrhosis and hepatocellular carcinoma in adults. Studies by Sveger in Sweden have shown that only a subgroup of the population with homozygous PiZZ α₁-AT deficiency develop clinically significant liver injury. Other studies have shown that the mutant α₁-AT Z molecule undergoes polymerization in the endoplasmic reticulum and that a subpopulation of α₁-AT-deficient individuals may be susceptible to liver injury because they also have a trait that reduces the efficiency by which the mutant α₁-AT Z molecule is degraded in the endoplasmic reticulum.     

Human GABA, Receptor αl and α3 Subunits Genes and Alcoholism

γ-Aminobutyric acid (GABA) is the major inhibitory neurotransmitter in the brain. GABA effects are largely mediated by binding to the postsynaptic GABA_A receptor, causing the opening of an integral chloride-ion channel. The GABA_A antagonists picrotoxin and bicuculline reduce some ethanol-induced behaviors, such as motor impairment, sedation, and hypnosis. The role of this receptor in alcoholism is further supported by effective alleviation of alcohol withdrawal symptoms by GABA_A agonists. To determine the role of the GABA, receptor (GABR) genes in the development of alcoholism, we have used α₁ and α ₃ simple sequence repeat polymorphisms in a sample of unrelated alcoholics, alcoholic probands with both parents, and psychiatrically normal controls. For the GABRα₁ gene, the differences between allele frequencies, when all alleles were compared together, were not significant between total alcoholics, subtypes of alcoholics, and normal controls. However, for GABRα₃, the differences between total alcoholics and normal controls were significant when all alleles were compared together. The differences between subtypes of alcoholics and normal controls were not significant. The results of haplotype relative risk analysis for both genes, GABRα₁ and GABRα₃, were also negative. It is possible that the sample size in the haplotype relative risk is too small to have power to detect the differences in transmitted versus nontransmitted alleles. There is a need for a replication study in a large family sample, that will allow haplotype relative risk or affected sib-pair analysis.     

Globin Synthesis in Sideroblastic Anaemia I α AND β PEPTIDE CHAIN SYNTHESIS

S ummary . The in vitro synthesis of the α and β peptide chains of globin have been measured in 11 patients suffering from sideroblastic anaemia (four congenital and seven idiopathic acquired). In the I0 patients who were anaemic the findings were similar. The synthesis of the globin chains was found to be defective in two respects; firstly, synthesis was asynchronous with an apparent deficiency of the synthesis of α chains, and, secondly, a large proportion of both α and β chains synthesized were not associated with haem but were free in the cell in the form of αβ dimers. Addition of haem to the incubation mixture greatly stimulated the synthesis of both chains, removed the free dimer pool and appeared to stimulate a chain synthesis. The finding that a large proportion of the α and β chains synthesized are not associated with haem but are free within the cell as a dimer pool, is very strong evidence that the underlying defect in sideroblastic anaemia is haem deficiency. The defective synthesis of a chains relative to β chains is as yet unexplained but may account for the low haemoglobin A₂ associated with this condition.     

The α-Galactose Specificity of Anti-Pk

Abstract. These studies indicate that α-galactose is the terminal and immunodominant sugar of the P^k determinant. Human anti-P^k and the 'anti-P^k' activity of salmon and trout protectins are strongly inhibited by α-galactosyl groups of galactose, disaccharides and macromolecules, e.g. P₁ substance. Removal of a-galactose from P₁ substance abolishes its ability to inhibit anti-P^k antibody activity.
Anti-P^k antibody has a narrow spectrum for terminal a-galactosyl groups of cell surface antigens defining those of P^k but not those of B, P₁ or P₂ cells, while all these cells are agglutinated by the fish roe protectins. We suggest that anti-P^k antibody selects a larger determinant than the terminal α-galactosyl group and the full determinant is structurally different from those of B, P₁ and P₂ antigens. By contrast, fish roe agglutinins bind to a part only of the α-galactosyl group, present in all these antigens.     

Allotypes of Serum α2-Macroglobulin β-Lipoprotein and Immunoglobulins in the Domesticated Sheep (Ovis Aries)

Abstract. Antisera specific for allotypic markers carried by the serum α₂-macro-globulin, β-lipoprotein and IgGl and IgG2 were produced during cross-immunization experiments with sheep (Ovis aries). Two markers controlled by autosomal co-dominant genes, Ap ¹ and Ap ², were found on the α₂-macroglobulin; one marker controlled by an autosomal dominant Lp ¹ was found on the β-lipoprotein, two markers controlled by the autosomal codominants, Igl ¹ and Igl ², were found on the IgGl and one marker, controlled by Ig2 ¹ and linked to Igl ¹, was found on the IgG2. The immunoglobulin markers all occurred on the Fc fragments of the immunoglobulin molecules. There was no linkage between the Ap and Lp loci or between these and the immunoglobulin loci. A preliminary survey of the incidences of the markers in various flocks of sheep showed that the incidence of Lp ¹ and Igl ¹ was very much higher in Merinos than in the British breeds of sheep.     

α-Thalassaemia in the population of Cyprus

We have determined the α-thalassaemia (α-thal) determinants in 78 patients with Hb H disease from Cyprus; 25 were Turkish Cypriots and 53 were Greek Cypriots. Four deletional and three non-deletional α-thal alleles were present; the -α(3.7 kb) α-thal-2 and the —^MED-1α-thal-1 were most frequently seen; —^MED-II and -(α)^20.5 deletions occurred at considerably lower frequencies. About 15% of all chromosomes carried a non-deletional α-thal-2 allele; of these the 5 nucleotide (nt) deletion at the first intervening sequence (IVS-I) donor splice site was present in ˜ 8% of all chromosomes. Two types of polyadenylation signal (poly A) mutations were observed. No striking frequency differences were seen between Greek and Turkish Cypriot patients. Combinations of the various types of α-thal resulted in eight different forms of Hb H disease. The phenotypes were comparable except for great variations in the level of Hb H which was highest (average ˜ 22%) in the 12 patients with the α^5ntα/—^MED-I combination. One patient with the same form of Hb H disease but with an additional β-thal (IVS-I-110, G → A) heterozygosity had a most severe microcytosis and hypochromia with < 1% Hb H. Variations in the level of Hb H might correlate with the severity of the disease, although this was not evident from the haematological data.     

Effect of α-Chain Precipitates on Bone Marrow Function in Homozygous β-Thalassaemia

S ummary . An autoradiographic study of protein synthesis by erythropoietic cells in liomozygous β-thalassaemia has shown that a high proportion of non-dividing, late polychromatic erythroblasts fail to become labelled when incubated with radioactive amino acids. It is possible that this abnormality and the previously described disturbance of cell proliferation in the early polychromatic erythroblasts result from damage by intracellular α-chain precipitates. This possibility has been investigated by correlating the extent of α-chain precipitation with protein or DNA synthetic activity in individual cells. Over 80% of late polychromatic cells with the largest α-chain inclusions failed to label with ³H-leucine or ³H-phenylalanine but 10–23% of cells with no inclusions were also unlabelled. None of the dividing, early polychromatic cells with moderate or large quantities of insoluble α-chains incorporated ³H-thymidine. These results support the hypothesis that a-chain precipitates are associated with and possibly responsible for the ineffectiveness of erythropoiesis in thalassaemia, provided it is assumed that such precipitates are continuously degraded or extruded. The latter assumption is necessary to account for the presence of several metabolically abnormal cells with no α-chain precipitates.     

Comparison of Haematological Features of the β0 and β+ Thalassaemia Traits in Jamaican Negroes

Haematological characteristics have been compared in 29 subjects with heterozygous β⁰ thalassaemia and in 33 subjects with heterozygous β⁺ thalassaemia, identified by the type of sickle cell-β thalassaemia among close relatives, in a Jamaican Negro population. Total haemoglobin, MCV and MCH were significantly lower in the β⁰ type but the level of Hb A₂ was not significantly different. Individual values for MCV, MCH and Hb A₂ in the β⁺ type occasionally overlapped those in the normal population casting doubt on the adequacy of these criteria in identifying all cases of heterozygous β⁺ thalassaemia. The haematological differences are those which would be expected on theoretical grounds. The inability to confidently differentiate the two types of heterozygous β thalassaemia has implications for genetic counselling. The inability to distinguish heterozygous β⁺ thalassaemia from normals on any single haematological index suggests that surveys depending on estimations of Hb A₂ or on MCV alone may have underestimated the prevalence of the β⁺ thalassaemia gene.     

SYNTHESIS AND BIOLOGICAL ACTIVITY OF α-AZAPEPTIDES: α-AZA-ANALOGUES OF LUTEINIZING HORMONE RELEASING HORMONE

The term 'α-azapeptides'is applied to analogues derived by change of one or more of the α-CHs of amino-acid residues in peptides by N; in such analogues the overall polarity of the molecule and the spacing of side-chain residues is preserved, but stability towards peptidases may be increased because of the changed conformational situation at the residue or residues involved in the change. Three α-aza-analogues of LHRH, i.e. azaglycine⁶-, azalanine¹⁰-LHRH, and two α-aza-analogues of des-His-LHRH, i.e. azalglycine⁶-and azalanine ⁶-des-His-LHRH in inducing ovulation in androgen-sterilized, constant-oestrus rats, but less potent than LHRH in causing LH release in immature male rats. Evidence of increased duration of action was not obtained. The two aza-analogues of des-His-LHRH were neither agonists nor antagonists in these two test systems.     

Haemoglobin Constant Spring has an unstable α chain messenger RNA

Haemoglobin Constant Spring (Hb CS) is a variant with an elongated α-chain associated with an α⁺ thalassaemia phenotype. The amount of α mRNA relative to β mRNA in reticulocytes was reduced in carriers of Hb CS by an amount equivalent to the reduction observed in carriers of α⁺ thalassaemia. In a patient with Hb CS-H disease there was greater α/β mRNA ratio in bone marrow nuclear RNA than in the peripheral blood. Furthermore, all the α mRNA in the patient's peripheral blood was derived from the α1 (α^A) gene. The data suggest that α^CS mRNA is unstable and degraded in the cytoplasm. This instability may be due to destabilization of a specific sequence in the 3'non-coding region during translation.