Yoshiro Ohta

Hemoglobin Yoshizuka (G10(108)β asparagine→aspartic acid): a new variant with a reduced oxygen affinity from a Japanese family

During the course of a survey, a new hemoglobin, designated hemoglobin Yoshizuka, has been encountered in a Japanese family. Clinically, mild anemia was noted in five of six heterozygous individuals but no other significant abnormalities were found. Hemoglobin Yoshizuka is characterized by the substitution of aspartic acid for asparagine at the tenth residue of the G helix in the beta-chain. Reduced oxygen affinity with almost normal heme-heme interaction was found to be a property of this abnormal hemoglobin. The asparagine residue G10(108)beta lies in the internal cavity of the tetrameric molecule and its main chain carbonyl is thought to be hydrogen bonded to histidine G10(103)alpha at the region of contact between alpha- and beta-chains. It would appear likely that the introduction of a carboxyl group into the central cavity might result in interactions between the polar groups and the substituted side chain, disrupting the system of hydrogen bonds which contribute to the stability of the contacts between unlike subunits.

Frequency and Distribution of Structural Variants of Hemoglobin and Thalassemic States in Western Japan

Hemolysates from 100,000 people who visited the Kyushu University Hospital and affiliated hospitals during the past 15 years were screened for hemoglobinopathies using electrophoresis on thin-layer starch gel; those exhibiting an abnormality were characterized further on clinical, biochemical, and genetic grounds. Of about 97,000 adult and 3,140 cord blood samples, 29 contained electrophoretically detectable abnormalities in the heterozygous condition. Another 17 samples had quantitative changes in the levels of the minor hemoglobin components. Of the thalassemic conditions, 12 involved beta-thalassemia, 3 alpha-thalassemia, 1 delta beta-thalassemia, and 1 delta-thalassemia. Among 45 carriers of beta-thalassemia from 12 families, 5 were noted to have thalassemia intermedia since they exhibited much more severe hemolytic syndromes than those with typical beta-thalassemia minor. The frequency with which we could detect a structural variant of Hb A in the adults by electrophoresis was one in 3,800 samples. About one in 8,000 carried a beta-thalassemia gene.

Hemoglobin sawara: α 6(A4) aspartic acid → alanine

Abstract In a survey of a Japanese population for abnormal hemoglobins, a new variant of human adult hemoglobin was found: hemoglobin Sawara, in which a residue of aspartic acid in position 6(A 4 ) of the α-chain is replaced by one of alanine. There were no pathological findings associated with this hemoglobin variant.