TYPE Hispanic (epsilongammadeltabeta)°-Thal (see Fig. 17)
CAUSE The deletion involves ~30 kb of DNA sequences 5' to the epsilon gene. It extends from -9.5 to -39 kb 5' of the epsilon gene, and includes three of the four DNase I hypersensitive sites at -10, -14.7, and -18 kb (5'HS-2, 5'HS-3, and 5'HS-4, respectively) 5' to the epsilon gene. The remaining sequences of the beta gene complex, including the DNase I 5'HS-1 at -6.1 kb and all other structural genes in cis to the deletion are intact but nonfunctional.
DETECTION Gene mapping with different enzymes and probes.
PHENOTYPE The condition presents as neonatal hemolytic anemia with decreased globin chain synthesis, and develops into a benign beta-thal trait type of abnormality. The proband had a neonatal hemolytic anemia at birth, requiring an exchange transfusion. Microcytosis and hypochromia consistent with thalassemia trait were reported at birth. The patient had the following hematology at 2 months after birth and at age 11 years.

Proband Hb
Hb A2
Hb F
2 months 7.9 70.0 n.d. 2.9 9.8 n.d.
11 years 11.6 59.0 19.8 3.5 0.24 2.8

DISTRIBUTION Found in a Hispanic family; the betaS gene was present in cis to the deletion which was not expressed.
1. Driscoll, M.C., Dobkin, C.S., and Alter, B.P.: Proc. Natl. Acad. Sci. USA, 86:7470, 1989.

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.