TYPE Thai (deltabeta)°-Thal (see Fig. 14)
CAUSE An ~12.5 kb deletion that extends from the 3' end of the delta gene to the 3' end of the beta gene, removing part of the L1 repetitive sequences. The Thai deletion is very similar to the Sicilian and Laotian (deltabeta)°-thal, both in size and the location of the breakpoints.
DETECTION Gene mapping of DNA with different restriction enzymes and hybridization to several probes. The 5' end of the deletion was located in the delta-IVS-II with the BamHI site intact but the EcoRI site deleted. Thus, the 5' end of the Thai (deltabeta)°-thal is located at or near the 5' breakpoint of the Sicilian (deltabeta)°-thal. The 3' end is located 1 kb upstream from the 3' site of the Sicilian deletion.
PHENOTYPE The subject had a Hb level at the lower limit (12.2 g/dl) of normal. Mild microcytosis (MCV 74 fl) and hypochromic red cells (MCH 23 pg) were observed, Hb A2 is normal (2.7%), and Hb F elevated (9.9%).
DISTRIBUTION Found in a middle-aged woman from Thailand.
1. Trent, R.J., Svirklys, L., and Jones, P.: Hemoglobin, 12:101, 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.