IVS-II-5.(G-@C).html


MUTATION		IVS-II-5 (G->C)

AMINO ACID REPLACEMENT		None
TYPE OF BETA-THAL		beta⁺ (severe)
MECHANISM		The G->C mutation greatly reduces the efficiency of splicing at the normal 5' site of the IVS-II (see G->T at IVS-I-5)
IDENTIFICATION		Amplification of the beta-globin gene; sequencing; dot-blot analysis with allele specific probes
HEMATOLOGY IN HETEROZYGOTE(S)		The mother is the likely beta-thal heterozygote: Hb 11.5 g/dl; Hb A₂ 4.1%; Hb F 1.8%
HEMATOLOGY IN HOMOZYGOTE(S)		Not reported
OCCURRENCE		In a Chinese family from Guangxi Province, P.R. China
HAPLOTYPE		Not reported
FOUND IN COMBINATION WITH ABNORMAL HB(S)		Not reported
FOUND IN COMBINATION WITH BETA-THAL ALLELE(S)		Found in three Chinese patients together with the codons 41/42 (-TTCT) frameshift: Hb 5.0-6.7 g/dl; Hb A₂ 6.2, 7.9, 9.1%; Hb F 11.2-12.3%; patients were transfused
OTHER INFORMATION		There is a possibility of Hb E being present in the blood used for transfusion explaining the high Hb A₂ levels in the compound heterozygotes


REFERENCES
1.		Jiang, N.H., Liang, S., Su, C., Nechtman, J.F., and Stoming, T.A.: Hemoglobin, 17:563, 1993.

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.