MUTATION		Codon 127 (A->C); CAG(Gln)->CCG(Pro)
AMINO ACID REPLACEMENT		Gln->Pro (Hb Houston)
TYPE OF BETA-THAL		Dominant inclusion body beta-thal trait
MECHANISM		The mutation results in the synthesis of an abnormal betaX chain which is highly unstable and is rapidly removed by proteolysis, resulting in this TYPE OF BETA-THAL
IDENTIFICATION		Amplification of the beta-globin gene; DNA sequencing
HEMATOLOGY IN HETEROZYGOTE(S)		An 8-month-old Caucasian boy with anemia (Hb 8.0-9.0 g/dl) reticulocytosis; MCV 67 fl; MCH 21.5 pg; Hb A2 4.7%; Hb F 24.0%; the mother required transfusions and was splenectomized (Hb 8.7 g/dl; MCV 80 fl; 274 nRBC/100 WBC; Hb A2 5.7%; Hb F 10.0%); the grandmother was also splenectomized and was occasionally transfused
HEMATOLOGY IN HOMOZYGOTE(S)		None
OCCURRENCE		In a Caucasian family (proband, mother, grandmother) (British background)
HAPLOTYPE		Not reported
FOUND IN COMBINATION WITH ABNORMAL HB(S)		None
FOUND IN COMBINATION WITH BETA-THAL ALLELE(S)		None
OTHER INFORMATION		The betaX chain could not be isolated by electrophoretic or chromatographic procedures
NOTE		This allele was reported as CAG->CGG; the authors have corrected this unfortunate mistake to CAG->CCG (personal communication)

REFERENCES
1.		Kazazian, H.H., Jr., Dowling, C.E., Hurwitz, R.L., Coleman, M., Stopeck, A., and Adams, J.G., III: Blood, 79:3014, 1992.

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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.