Hb Constant Spring (or CS) alpha142, Term->Gln (TAA->CAA in alpha2);
modified C-terminal sequence:
Phe-Leu-Val-Phe-(172)Glu-COOH (31 additional residues)
HEMATOLOGY Mild hypochromia and microcytosis in the heterozygote
ELECTROPHORESIS Two components moving slower than Hb A2 at alkaline pH
CHROMATOGRAPHY Hb X was isolated on Amberlite IRC-50 or DEAE-Sephadex columns; separation by cation exchange HPLC not satisfactory
STRUCTURE STUDIES Tryptic digestion; separation of peptides by fingerprinting or cation exchange chromatography; amino acid analysis; sequencing
DNA ANALYSES A TAA->CAA mutation at codon alpha142 (alpha2); the Hb CS abnormality is now routinely identified through DNA analyses (sequencing of amplified DNA; dot-blot analysis with specific probes; RFLP analysis)
OCCURRENCE Found in modest frequencies in many SE Asian populations (China, Vietnam, Laos, Cambodia, India, Malaysia, Indonesia, etc.)
OTHER INFORMATION Quantity in heterozygotes 1-2%; homozygotes have higher quantities; Hb CS in combination with an alpha-thal-1 (mostly the SEA type) results in a rather severe form of Hb H disease
1. Milner, P.F., Clegg, J.B., and Weatherall, D.J.: The Lancet, i:729, 1971.
2. Clegg, J.B., Weatherall, D.J., and Milner, P.F.: Nature, 234:337, 1971.
3. Efremov, G.D., Wrightstone, R.N., Huisman, T.H.J., Schroeder, W.A., Hyman, C., Ortega, J., and Williams, K.: J. Clin. Invest., 50:1628, 1971.
4. Lie-Injo, L.E., Baer, A., Lewis, L.N., and Welch, Q.B.: Am. J. Hum. Genet., 25: 382, 1973.
5. Kan, Y.W., Todd, D., and Dozy, A.M.: Br. J. Haematol., 28:103, 1974.
6. Lie-Injo, L.E., Ganesan, J., Clegg, J.B., and Weatherall, D.J.: Blood, 43:251, 1974.
7. Xu, X-M., Zhang, J-Z., and Li, S-K.: Hemoglobin, 18:61, 1994.
8. Smetanina, N.S., Leonova, J.Y., Levy, N., and Huisman, T.H.J.: Acta Haematol., 94:144, 1995.

This material is from the book A Syllabus of Human Hemoglobin Variants (1996) by Titus H.J. Huisman, Marianne F.H. Carver, and Georgi D. Efremov, published by The Sickle Cell Anemia Foundation in Augusta, GA, USA. Copyright © 1996 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 written permission.