MUTATION		TAA->TAT at codon 142 of the alpha2 gene
AMINO ACID REPLACEMENT		Stop codon->Tyr + 30 additional amino acids (Hb Paksé)
TYPE OF ALPHA-THAL		alpha-Thal-2 [alpha(T)alpha/alphaalpha]
MECHANISM		The A->T mutation results in an extended alpha chain (+ 31 residues) at the C-terminus; a new stop codon is formed at codon 173
IDENTIFICATION		Amplification of the alpha2-globin gene; DNA sequencing; dot-blot analysis with allele specific probes
HEMATOLOGY IN HETEROZYGOTE(S)		Father of the proband: Hb 14.3 g/dl; MCV 83.5%; he was also heterozygous for Hb E (Ref. 1)
HEMATOLOGY IN HOMOZYGOTE(S)		Not observed
OCCURRENCE		In a few Laotian families
HAPLOTYPE		Not determined
FOUND IN COMBINATION WITH ABNORMAL HB(S)		Not reported
FOUND IN COMBINATION		With alpha-thal-1 (probably SEA); this proband had Hb H disease: Hb 8.1 g/dl; MCV 65 fl; Hb A2 0.8%; Hb H 8.8% (Ref. 1). With the -alpha(3.7 kb) alpha-thal-2 (Ref. 2). With the nondeletional Hb Constant Spring (Ref. 2)
OTHER INFORMATION		The protein Hb Paksé has not been recovered; quantity in the heterozygote <0.2%

REFERENCES
1.		Waye, J.S., Eng, B., Patterson, M., Chui, D.H.K., and Olivieri, N.F.: Blood, 83:3418, 1994.
2.		Smetanina, N.S., Leonova, J.Ye., Levy, N., and Huisman, T.H.J.: Acta Haematol., 94:144, 1995.

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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.