TYPE Dutch (epsilongammadeltabeta)°-Thal (see Fig. 17)
CAUSE The deletion removes 99.4 kb DNA extending from 2.5 kb upstream from the beta gene to ~57 kb 5' to the epsilon gene. The beta gene and its flanking sequences are intact, while the epsilon, gamma, and delta genes are deleted.
DETECTION It was initially thought that this condition could be the caused by a point mutation or a small deletion in the beta gene. This was eliminated by sequencing the entire beta gene. Gene mapping with different enzymes and probes.
PHENOTYPE The subjects have the hematological characteristics of a heterozygous beta°-thal, except for normal Hb A2 values. Hematological data are as follows: Hb 9.7 g/dl; RBC 4.5 x 1012/l; MCV 67 fl; Hb A2 3.2%; Hb F 1.0%; alpha/beta ratio 2.0. During postnatal development a chronic microcytic anemia persists in the carriers, with normal or near normal reticulocyte counts and bilirubin levels.
DISTRIBUTION Found in seven members of a Dutch family from The Netherlands.
1. Van der Ploeg, L.H.T., Konings, A., Oort, M., Roos, D., Bernini, L., and Flavell, R.A.: Nature, 283:637, 1980.

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.