Thai.Ggamma(Agammadeltabeta)0-Thal.html


TYPE		Thai ^Ggamma(^Agammadeltabeta)°-Thal (see Fig. 16)

CAUSE		A ~70 kb deletion that starts at the HindIII site 3' to the ^Ggamma gene, and extends to a region more than 45 kb from the 3' end of the beta gene. The proband carried in trans a beta°-thal (IVS-II-654, C->T) and an ^Agamma-thal caused by a 5 kb deletion. Thus, three thalassemia abnormalities were present in the proband: a) the Thai ^Ggamma(^Agammadeltabeta)°-thal allele on one chromosome; b) the IVS-II-654 (C->T) beta°-thal allele and the deletional gamma-thal on the second chromosome.
DETECTION		Gene mapping with different probes and enzymes. The 3' end of the deletion was mapped; it is located in a region more than 45 kb from the 3' end of the beta gene. The total length of this deletion is estimated to be ~70 kb.
PHENOTYPE		The proband who is a compound heterozygote for this deltabeta-thal and beta-thal (IVS-II-654, C->T) presented clinically as thalassemia intermedia with a mild anemia, jaundice, and hepatosplenomegaly. One of her siblings with the same genotype, was splenectomized. Her father and two siblings are simple heterozygotes for the (^Agammadeltabeta)°-thal with elevated Hb F levels which was distributed pancellularly in the erythrocytes: Hb 14 and 13.6 g/dl; MCV 74 and 93 fl; MCH 25 and 30 pg; MCHC 34 and 23 g/dl; Hb A₂ 1.7 and 2.5%; Hb F 20.0 and 17.2%; Hb F was composed mainly of ^Ggamma chains. The hematological data for the proband are: Hb 8.9 g/dl; MCV 83 fl; MCH 23 pg; MCHC 27 g/dl; reticulocytes 2.4%; Hb A₂ 2.7%; Hb F 65.6%; F-cell distribution is homogeneous; Hb F had mainly ^Ggamma chains.
DISTRIBUTION		The Thai ^Ggamma(^Agammadeltabeta°-thal was found in a large family. Five of the offspring inherited the Thai deletion from their father. Two of the five children also inherited a beta°-thal (IVS-II-654, C->T) mutation from their mother. The same (^Agammadeltabeta) deletion was found in another Thai family.


REFERENCES
1.		Fucharoen, S., Winichagoon, P., Chaicharoen, S., and Wasi, P.: Eur. J. Haematol., 39:154, 1987.
2.		Winichagoon, P., Fucharoen, S., Thonglairoam, V., and Wasi, P.: Hemoglobin, 14:185, 1990.

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.