Y. Ohba

Hb himeji or β140 (H18) ALA→ASP a slightly unstable hemoglobin with increased βN-terminal glycation

A fast-moving abnormal hemoglobin found in a diabetic patient was identified as beta 140 (H18) Ala----Asp. It comprised about 40% of the total hemoglobin. The beta N-terminal glycation in the abnormal hemoglobin was estimated to be 3 times as much as that in Hb A in the same blood sample. The abnormal hemoglobin was slightly unstable. Oxygen affinity of the stripped hemoglobin was decreased, but that of red cells from the carrier was slightly higher than normal because of the reduced effect of 2,3-diphosphoglycerate.

Hemoglobin Agenogi (α2β290lys), a slow-moving hemoglobin of a Japanese family resembling Hb-E☆

Abstract A new slow-moving hemoglobin, designated Hb Agenogi, was discovered in a Japanese family in 1965. This hemoglobin was not associated with any clinical or hematological abnormality. It resembled closely Hb-E in electrophoretic and Chromatographic behaviour. Detailed chemical study, however, has established that this hemoglobin can be expressed by the formula α290Lys-a new variant of Hb-A which has not yet been recorded in the list of the abnormal hemoglobins hitherto known to us.

Characterization of β-Thalassemia Mutations Among the Japanese

Characterization of beta-thalassemia mutations were attempted for 29 Japanese families clinically diagnosed as having beta-thalassemia. Following the identification of a mutation by cloning and sequencing, all families were screened for this particular mutation, using biotinylated allele-specific oligonucleotide probes. Seven different mutations were detected in 17 families: Six families had the frameshift mutation at codons 41/42, resulting from a 4 nucleotide deletion (TTCTTT----TT); four had the deletion at codons 127/128 (CAGGCT----CCT); and three had the TATA box mutation at nucleotide -31 (A----G). Four additional families had mutations at codon 24 (GGT----GGA), codon 26 (GAG----AAG), IVS-II-654 (C----T) and codon 110 (GTG----CCG), respectively. The newly discovered deletion mutation at codons 127/128, and mutations at nucleotide -31, and at codon 110 are peculiar to Japanese, and have not been found in any other ethnic group. The haplotypes of the beta-globin gene cluster were also determined. Some of the haplotypes and beta-thalassemia mutations are identical to those reported in the Chinese population. However, it is noteworthy that nearly half of the beta-thalassemia mutations were unique to Japanese.

Two β-Thalassemia Mutations in Japan: Codon 121 (Gaa→Taa) and IVS-I-130 (G→C)

(1992). Two β-Thalassemia Mutations in Japan: Codon 121 (Gaa→Taa) and IVS-I-130 (G→C) Hemoglobin: Vol. 16, No. 4, pp. 295-302.

Survey of cord blood Hemoglobin in Japan and Identification of two new γ Chain Variants

Two γ chain variants were discovered during a survey of 2,569 cord bloods of Japanese. One was the first case with mutation of the T-γ; chain, i. e. Hb F Yamaguchi or γ 80 (EF 4) Asp → Asn (75 Thr, 136 Ala). It comprised 33.6 % of Hb F, an unusually high percentage for a γ chain variant. The other concerned with the first report of substitution at E 16, i. e. Hb F Iwata or γ72 (E 16) Gly → Arg (75 Ile, 136 Ala). It comprised 11.0 % which is comparable to the values usually reported in an A-γ chain variant. No clinical consequences have been observed in association with the hemoglobin variants.

Urea polyacrylamide gel electrophoresis of PCMB precipitate as a sensitive test for the detection of the unstable hemoglobin subunit

A sensitive test for the detection of the abnormal subunit of unstable hemoglobins is described. The unstable hemoglobin subunit was selectively precipitated by paramercuribenzoic acid treatment of the carboxy hemolysate, and the precipitate was studied by urea polyacrylamide gel electrophoresis for globin composition. The test enabled the detection of an electrophoretically silent, alpha-chain unstable variant comprising only 1% of total hemoglobin. Other applications included the demonstration of Hb Köln in a cord blood, and the detection and purification of very slightly unstable hemoglobin variants.

Abnormal Hemoglobins in Japan

The incidence of abnormal hemoglobins among the Japanese is estimated at one per 2,700 through systematic surveys (chiefly by use of electrophoresis of hemolysates) of 160,000 people, which have been carried out for these twenty years. About 40 variants of abnormal hemoglobins were detected and identified by chemical analysis. More than ten are in the process of identification.

Unstable Hemoglobins in Japan

Ten unstable hemoglobins have been identified in 14 Japanese families (Table I). Five of them which have never been found in other countries are Hb Hirosaki, Hb Iwata, Hb Tochigi, Hb Mizuho, and Hb Toyoake. Hb Koln has been found in four independent families. Eight cases (57% of the total number of families) appear to have occurred by de novo mutation. We will briefly describe two new unstable hemoglobins, Hb Toyoake and Hb Iwata.

A New Unstable, High Oxygen Affinity Hemoglobin: Hb Nagoya Or β97 (Fg4) His→Pro

An unstable hemoglobin was detected by isopropanol and heat precipitation tests in a 49-year-old Japanese man suffering from acute exacerbation of a chronic hemolytic disorder which was apparently triggered by infection of cholelithiasis. One of his two sons carried the same abnormal hemoglobin, and was jaundiced, but otherwise healthy, without anemia. The abnormal hemoglobin focused at a slightly more anodic position than Hb A in thin layer polyacrylamide gel electrofocusing. The abnormal beta chain emerged after normal beta chain in reverse phase high performance liquid chromatography of the hemolysate. It comprised 16.7% and 25.5% of the total beta chain in the propositus and his son, respectively. The partially heme-depleted abnormal beta subunit was precipitated with p-chloromercuribenzoic acid, and the abnormal beta chain was isolated by urea CM-cellulose column chromatography. Structural analysis demonstrated substitution of proline for histidine at position 97 (FG4) in the beta chain. The abnormal hemoglobin was purified by ion-exchange column chromatography. It showed a hyperbolic oxygen equilibrium curve indicating a high oxygen affinity and the absence of cooperative intersubunit interaction. Subunit dissociation seemed to be slightly enhanced. The variant was markedly susceptible to oxidation and rapidly lost heme upon oxidation.

A New Unstable Hemoglobin, Hb Yokohama β31(B13)LEU → Pro, Causing Hemolytic Anemia

A new unstable hemoglobin was found in a 33-year-old Japanese woman with a history of chronic, partially compensated hemolytic anemia. An electrophoretically silent unstable β chain was prepared by PCMB precipitation and the amino acid substitution determined as β31(B13)Leu → Pro. Her son was a carrier of the same variant, who manifested milder symptoms.