TYPE Scottish-Irish (epsilongammadeltabeta)°-Thal (see Fig. 17)
CAUSE A large deletion that removes all the functional genes in the beta-globin gene cluster, including the 5'HS-1 to 5'HS-4 controlling region upstream from the epsilon gene. The deletion was mapped to be ~205 kb. DNA mapping, cloning and sequencing localized the 3' breakpoint to 263 bp 3' to the third exon of the beta gene.
DETECTION Gene mapping with several enzymes and probes; cloning and sequencing.
PHENOTYPE Affected individuals showed mild microcytosis and hypochromia. Basophilic stippling and target cells were frequently prominent in the peripheral blood. The Hb A2 levels were in the upper limit of normal (3.4-3.8%); Hb levels were low. Hematological and clinical phenotypes described in neonates with (epsilongammadeltabeta)°-thal are variable. They range from a severe life-threatening microcytic hemolytic anemia requiring blood transfusions to an asymptomatic condition. Two neonates with the Scottish-Irish deletion required blood transfusions and prolonged hospitalization.
DISTRIBUTION Found independently in two families of British descent.
1. Pirastu, M., Kan, Y.W., Lin, C.C., Baine, R.M., and Holbrook, C.T.: J. Clin. Invest., 72:602, 1983.
2. Trent, R.J., Williams, B.G., Kearney, A., Wilkinson, T., and Harris, P.C.: Blood, 76:2132, 1983.

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.