MUTATION Codons 38/39 [-ACC (Thr)]; deleted from the alpha1-globin gene
AMINO ACID REPLACEMENT Deletion of a threonine residue at position alpha38 or alpha39 (Hb Taybe)
TYPE OF ALPHA-THAL alpha-Thal-2 [alphaalpha(T)/alphaalpha]
MECHANISM The instability of the abnormal Hb results in a decrease in alpha chain synthesis
IDENTIFICATION Amplification; DNA sequencing
HEMATOLOGY IN HETEROZYGOTE(S) Hb 9.3-14.7 g/dl; MCV 69-85 fl; MCH 21-29 pg; Hb A2 and Hb F normal
HEMATOLOGY IN HOMOZYGOTE(S) Hb 7.3 g/dl; RBC 2.1 x 1012/l; PCV 0.244 l/l; MCV 117 fl; MCH 35 pg; reticulocytes 530 x 109/l (Ref. 1); severe hemolytic disease
OCCURRENCE In a few Arabian families living in Israel
HAPLOTYPE Not determined
FOUND IN COMBINATION WITH A poly A mutation in trans (alpha2; AATAAA->AATAAG; Ref. 2) resulting in severe hemolytic disease: Hb 8.5 g/dl; MCV 117.7 fl; reticulocytosis and folic acid deficiency; MCV 28.7 fl; Hb A2 1.3%. Blood transfusions are required; patient was splenectomized; Hb H was not detected but might be present in low quantities
OTHER INFORMATION The abnormal Hb can be detected by IEF; amount in the compound heterozygote estimated at ~5%; heat stability test on freshly collected sample was positive; structural analyses have confirmed the loss of a threonine residue
1. Galacteros, F., Girodon, E., M'Rad, A., Martin, J., Goossens, M., Jaber, L., Cohen, I.J., Tamar, H., Goshen, Y., Zaizov, R., and Wajcman, H.: C.R. Acad. Sci., 317:437, 1994.
2. Pobedimskaya, D.D., Molchanova, T.P., Streichman, S., and Huisman, T.H.J.: Am. J. Hematol., 47: 198, 1994.

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.