TYPE Croatian (epsilongammadeltabeta)°-Thal (see Fig. 17)
CAUSE The condition is characterized by a large deletion removing at least 148 kb; the 5' end is located between the TaqI and BglII sites, ~55 and ~22 kb 5' to the epsilon gene, respectively. The 3' breakpoint is located beyond the BglII site 82 kb 3' to the beta gene.
DETECTION Gene mapping with different probes and enzymes.
PHENOTYPE Heterozygotes have a mild anemia with microcytosis and hypochromia, normal levels of Hb A2, and slightly raised Hb F levels. Low MCV (57-66 fl), MCH (19-22 pg), and Hb levels (9.4-11.9 g/dl) are observed. Bone marrow examination revealed hyperplasia and the erythrocyte survival (measured by 51Cr) was 17 days (normal 26-30 days). The Hb F levels were ~2% with the normal Ggamma:Agamma ratio of 40-60%. The in vitro chain synthesis ratio (alpha/beta) for heterozygotes was 1.66.
DISTRIBUTION Found in a Croatian family from Zagreb, Croatia.
1. Diaz-Chico, J.C., Huang, J.H., Juricic, D., Efremov, G.D., Wadsworth, L.D., and Huisman, T.H.J.: Acta Haematol., 80:79, 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.