MUTATION Codon 110 (T->C); CTG(Leu)->CCG(Pro)
 
AMINO ACID REPLACEMENT Leu->Pro (Hb Showa-Yakushiji)
TYPE OF BETA-THAL beta+
MECHANISM The T->C mutation results in the synthesis of an extremely unstable betaX chain which is rapidly catabolized by proteolysis
IDENTIFICATION Cloning; DNA sequencing; MspI digestion and Southern blotting because a recognition site is created by this mutation
HEMATOLOGY IN HETEROZYGOTE(S)
Proband Sister Mother
Hb (g/dl) 7.6 9.8 9.0
MCV (fl) 56.0 60.0 60.0
MCH (pg) 17.8 19.1 20.0
Reticulocytes (%) 2.4 4.1 2.1
Bilirubin (mg/dl) 0.46 0.72 0.50
Hb F (%) 1.3 2.0 2.0
Hb A2 (%) 5.2 5.3 5.3
Heat denaturation test (50°C) (%) (-) (-) (-)
Isopropanol test (-) (-) (-)
Electrophoresis (starch, IEF) None None None
beta/alpha chain synthesis ratio 0.8 0.8 0.7

HEMATOLOGY IN HOMOZYGOTE(S) Not reported
OCCURRENCE In a Japanese family (proband, mother, sister), in a second (unrelated) Japanese individual, and in some UAE families
HAPLOTYPE Not reported
FOUND IN COMBINATION WITH ABNORMAL HB(S) Not reported
FOUND IN COMBINATION WITH BETA-THAL ALLELE(S) Not reported
OTHER INFORMATION No abnormal peak was observed by reversed phase HPLC when the Hb from reticulocytes, incubated with isotopically labeled amino acids, was analyzed
       
REFERENCES
1. Kobayashi, Y., Fukumaki, Y., Komatsu, N., Ohba, Y., Miyaji, T., and Miura, Y.: Blood, 70:1688, 1987.
2. Hattori, Y., Yamane, A., Yamashiro, Y., Matsuno, Y., Yamamoto, Ki., Yamamoto, Ku., Ohba, Y., and Miyaji, T.: Hemoglobin, 13:657, 1989.
3. Ohba, Y., Hattori, Y., Harano, T., Harano, K., Fukumaki, Y., Ideguchi, H., Cho, H.I., and Park, S.S.: Hemoglobin, 21:191, 1997.


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.