MUTATION		TAA->GAA at codon 142 of the alpha2 gene
AMINO ACID REPLACEMENT		Stop codon->Glu + 30 additional amino acids (Hb Seal Rock)
TYPE OF ALPHA-THAL		alpha-Thal-2 [alpha(T)alpha/alphaalpha]
MECHANISM		The T->G mutation results in an extension of the alpha chain at the C-terminus with 31 amino acids; a new stop codon is present at codon 173
IDENTIFICATION		By protein analysis; amplification of the alpha2-globin gene and sequencing
HEMATOLOGY IN HETEROZYGOTE(S)		Hb 10.3 g/dl; MCV 72 fl; MCH 23 pg; Hb A2 2.8%; Hb Seal Rock 4.3%
HEMATOLOGY IN HOMOZYGOTE(S)		None
OCCURRENCE		In a Black family
HAPLOTYPE		Not determined
FOUND IN COMBINATION WITH ABNORMAL HB(S)		Not reported
FOUND IN COMBINATION		With the -alpha(3.7 kb) deletion; this individual had a hematology comparable to mild Hb H disease: Hb 9.8 g/dl; MCV 77.6 fl; MCH 23.3 pg; Hb A2 2.7%; Hb Seal Rock 4.8-6.2%
OTHER INFORMATION		None

REFERENCES
1.		Bradley, T.B., Wohl, R.C., and Smith, E.J.: Clin. Res., 23:131A, 1975.
2.		Fairbanks, V., Merritt, D., Rodgers, D., Thibodeau, S., Steinberg, M., Coleman, M., and Jones, R.: Blood, 86:657a (Suppl. 1), 1995.
3.		Merritt, D., Jones, R.T., Head, C., Thibodeau, S.N., Fairbanks, V.F., Steinberg, M.H., Coleman, M.B., and Rodgers, G.P.: Hemoglobin, in press, 1997.

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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.