TYPE Irish (epsilongammadeltabeta)°-Thal (see Fig. 17)
CAUSE A large deletion with a minimum size of 205 kb extending from at least 65 kb 5' to the epsilon gene, thus removing all the major controlling sequences (5'HS-1 to 5'HS-4). This deletion extends for at least 90 kb 3' to the beta gene and ends near the 3' deletion breakpoints associated with HPFH-1, HPFH-2, and the Spanish deltabeta°-thal.
DETECTION Gene mapping with different enzymes and probes.
PHENOTYPE Heterozygotes have microcytic anemia and imbalanced alpha/beta globin chain synthesis ratios. They all had normal Hb A2 and Hb F levels. A typical hematology of an affected individual was: Hb 13.6 g/dl; MCV 65.3 fl; MCH 19.8 pg; Hb A2 3.0%; Hb F 1.1%; alpha/beta ratio 2.7. Blood smear showed anisocytosis and poikilocytosis.
DISTRIBUTION Found in a large Irish family.
1. Fortina, P., Delgrosso, K., Werner, E., Haines, K., Rappaport, E., Schwartz, E., and Surrey, S.: Hemoglobin, 15:23, 1991.

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.