TYPE Japanese (deltabeta)°-Thal (see Fig. 14)
CAUSE A very large deletion including the psibeta, delta, and beta genes. The 5' breakpoint is located between 2134 and 2137 bp 3' to the poly A site of the Agamma gene, and the 3' breakpoint extending further than any other deletional mutant characterized thus far.
DETECTION Gene mappping with different probes and enzymes. The 5' breakpoint was analyzed by isolating a clone spanning the Japanese deltabeta-thal deletion junction.
PHENOTYPE Heterozygotes have a slight anemia and morphologic changes compatible with a mild thalassemia. Hb F is distributed unevenly in the RBCs. Hematological data: Hb 12.8 g/dl; RBC 6.04 x 1012/l; MCV 67 fl; MCH 21.2 pg; MCHC 31.7 g/dl; reticulocytes 1.0%; AgammaT 50.7%; Ggamma 49.3%; Hb A2 2.9%; Hb F 7.8%; non-alpha/alpha ratio 0.72. Homozygotes have a thalassemia intermedia-like condition. The deletion was first described in a 30-year-old Japanese woman who had moderate microcytosis and hypochromia with the following hematology: Hb 12 g/dl; RBC 4.85 x 1012/l; MCV 76 fl; MCH 24.7 pg; MCHC 32.6 g/dl; reticulocytes 2.4%; AgammaT 38.9%; Ggamma 61.1%; Hb A2 0%; Hb F 100.0%; non-alpha/alpha ratio 0.44. The blood film showed moderate anisocytosis and poikilocytosis. The chromosome with this deltabeta-thal deletion carries the ATA->ACA mutation at codon 75 (Ile->Thr; Agamma).
DISTRIBUTION Found in Japanese families.
1. Matsunaga, E., Kimura, A., Yamada, H., Fukumaki, Y., and Takagi, Y.: Biochem. Biophys. Res. Commun., 126:185, 1985.
2. Shiokawa, S., Yamada, H., Takihara, Y., Matsunaga, E., Ohba, Y., Yamamoto, K., and Fukumaki, Y.: Blood, 72:1771, 1988.

This material is from the book A Syllabus of Thalassemia Mutations (1997) by Titus H.J. Huisman, Marianne F.H. Carver, and Erol Baysal, published by The Sickle Cell Anemia Foundation in Augusta, GA, USA. Copyright © 1997 by Titus H.J. Huisman. All rights reserved. Neither this work nor any part may be reproduced or transmitted in any form or by any means, electronic or mechanical, microfilming and recording, or by any information storage and retrieval systems, without permission in writing from the Author.