Gerald Apell

THE PRESENT STATUS OF THE HETEROGENEITY OF FETAL HEMOGLOBIN IN β‐THALASSEMIA: AN ATTEMPT TO UNIFY SOME OBSERVATIONS IN THALASSEMIA AND RELATED CONDITIONS*

t Laboratory o f Protein Chemistry, Department of Cell and Molecular Biology, Medical College of Georgia and Veterans Administration Hospital Augusta, Georgia 30902

The complete amino acid sequence of bovine liver catalase and the partial sequence of bovine erythrocyte catalase.

Division of Chetnistry and Chemical Engineering,

Nature of fetal hemoglobin in the Greek type of hereditary persistence of fetal hemoglobin with and without concurrent beta-thalassemia.

California Institute of Technology Pasadena, California 91 109 5 Department of Physiology and Biochemistry, Faculty o f Agriculture Department of Pediatrics, Faculty of Medicine University of Skopje Skopje, Yugoslavia Childrens Hospital of Los Angeles and Department of Pediatrics School of Medicine, University of Southern California Los Angeles. California 90027 * * Department of Hematology, Hadassah Medical School Hadassah University Hospital, Hebrew University Jerusalem, Israel

A Homozygote for the HbGγ Type of Foetal Haemoglobin in India: A Study of Two Indian and Four Negro Families

Abstract The data upon which the sequence of the 506 residues in the subunit of bovine liver catalase (BLC) is based are presented in detail. A partial sequence of bovine erythrocyte catalase (BEC) which accounts for 493 residues shows complete concordance with the BLC data. On the other hand, BEC has at least 517 residues, that is, an extension beyond the C terminus of the BLC data. Although normally BLC has only 506 residues, there is evidence that, at some point in its history, it also had the C-terminal extension. It is speculated that this extension is lost in BLC either through a different processing of the molecule in liver than in erythrocytes or by partial degradation in the first stages of catabolism.

Search for nonallelic structural genes for γ-chains of fetal hemoglobin in some primates

Extract: The fetal hemoglobin (Hb-F) of blood samples from 11 newborn babies (two normal infants, two sickle cell trait carriers, two Hb-C heterozygotes, two infants with Hb-SG disease, one infant with Hb-Richmond heterozygosity, one β-thalassemia heterozy-gote, and one infant with a heterozygosity for the hereditary persistence of fetal hemoglobin) and from 16 adults (eight normals, two Hb-S heterozygotes, one Hb-C heterozygote, and five SC patients) has been examined to determine the ratio of the two structurally different γ chains, namely the Gγ and Aγ chains. This ratio is about 2:3 in the Hb-F of the adults and, therefore, significantly different from the 3:1 ratio in the Hb-F of the newborn. This newborn ratio undergoes a considerable change between the 3rd and 4th months of life, at which time it approaches that of the Hb-F of adults.Speculation: The mechanism by which the gradual change from γ chain synthesis to β and δ chain synthesis is controlled remains unclear. However, the change in the ratio of production of structurally different γ chains as a function of postnatal age indicates a rather complex mechanism which probably involves an unequal repression of the γ chain structural genes. Any explanation of the mechanism must take into account the fact that the production of two genes, the Gγ and Aγ, is greatly decreased, whereas that of two other genes, the β and δ, is started. Perhaps a closely related or even identical mechanism controls not only the ratio of production of the Gγ and Aγ genes but also that of the β and δ genes.

Nature of Foetal Haemoglobin in F‐Thalassaemia

The fetal hemoglobin in the affected members of three Greek families with the hereditary persistence of fetal hemoglobin has only gamma-chains of the type with alanine in position 136. Although certain Negro families had been considered to have only this type of gamma-chains in their fetal hemoglobin, further studies required that they be reclassified. Consequently, the Greek cases are the sole examples of this class among the heterozygotes for the hereditary persistence of fetal hemoglobin. In Greek double heterozygotes for beta-thalassemia and the hereditary persistence of fetal hemoglobin, fetal hemoglobin is increased above the level of hemoglobin F in simple heterozygotes and gamma-chains with glycine in position 136 become apparent. In these individuals, gamma-chains with alanine in position 136 apparently derive from the chromosome for the hereditary persistence of fetal hemoglobin and are present in the hemoglobin F with gamma-chains of both types from the chromosome for beta-thalassemia. When these data are correlated with earlier knowledge of the genetic state of the Greek individuals, modifications of our previous ideas about deletions as the genetic basis of the hereditary persistence of fetal hemoglobin must be considered.

Amino acid sequences in the β-chains of adult bovine hemoglobins C-Rhodesia and D-Zambia ☆

Summary. The haemoglobin of a 9‐yr‐old boy from the area of Bombay has only haemoglobin F. The γ‐chains of this haemoglobin F are solely of Gγ type, and the child is considered to be a homozygote for hereditary persistence of foetal haemoglobin of the Gγ type. The same kind of haemoglobin F is also present in a second Indian family and in four American Negro families. One Negro family has an appreciably lower percentage of haemoglobin F in heterozygotes than the other five families. In some of the families certain individuals also have haemoglobin E or haemoglobin S in trans to the other condition and haemoglobin A is absent. Although it has been concluded that the hereditary persistence of foetal haemoglobin is present the condition is not expressed uniformly in all these families. Some of them have certain characteristics of F‐thalassaemia. It is possible that two conditions are, in reality, represented: perhaps some families have the hereditary persistence of foetal haemoglobin and others have F‐thalassaemia.

Chemical heterogeneity of fetal hemoglobin in subjects with sickle cell anemia, homozygous hb-c disease, sc-disease, and various combinations of hemoglobin variants

Peptide γCB-3 is the indicator of the presence and activity of nonallelic structural genes for the human γ-chain. An equivalent peptide has been isolated from the HbF of the marmoset (Saguinus fuscicollis), the rhesus monkey (Macaca mulatta), the orangutan (Pongo pygmaeus), and the gorilla (Gorilla gorilla gorilla). The sequence of γCB-3 from the marmoset and the rhesus monkey, although different from that of human γCB-3, gives no evidence of heterogeneity of the HbF. However, the HbF of the rhesus monkey is itself heterogeneous, and there probably is a difference in another part of the γ-chain. The γCB-3 peptide of the orangutan is definitely heterogeneous: the heterogeneity is in position 135, however, rather than in position 136 as in human γCB-3. The gorilla has the same type of heterogeneity at position 136 as does the human, but the proportions of the two types of chains might differ in the two species.

On the structure of the hemoglobins A, A2, and F in a Negro with homozygous β-thalassemia

The nature of Hb‐F was studied in 32 heterozygotes for F‐thalassaemia, in four homozygotes, and in four persons who have F‐thalassaemia in combination with β‐thalassaemia or Hb‐S. Analysis of the cyanogen bromide fragment γCB‐3 indicated that, in all heterozygotes, both Gγ and Aγ chains were present in Hb‐F in an average ratio of about 2:3. In the homozygotes and the double heterozygotes, both Gγ and Aγ chains were observed in an approximate ratio somewhat higher than 1:1. This pattern of γ chain synthesis is nonspecific for F‐thalassaemia but similar to that observed in the traces of Hb‐F of normal adults. In conjunctionwith existing information from other genetic studies, it may be concluded that the mutation in F‐thalassaemia is associated with a complete deficiency of β and σ chains from cis position together with an increased synthesis of γ chains that is directed by both Aγ and Gγ loci.