Hb Costa Rica	beta77(EF1)His->Arg

CONTACT		External
HEMATOLOGY		Normal in the carrier
ELECTROPHORESIS		Hb X can be separated from Hb A at alkaline pH (moves like Hb S)
CHROMATOGRAPHY		Excellent separation by DEAE-cellulose chromatography
STRUCTURE STUDIES		Tryptic digestion of isolated AE-betaX chain; separation of tryptic peptides by reversed phase HPLC; amino acid analysis
DNA ANALYSES		See below
FUNCTION STUDIES		Not determined
STABILITY		Stable
OCCURRENCE		Found in a Costa Rican female but not in her immediate relatives
OTHER INFORMATION		The expected CAC->CGC mutation at codon 77 could not be observed in genomic DNA or in cDNA. However, a small amount of beta-Costa Rica cDNA (or mRNA) could be detected by ASO and dot-blot analysis with 32P-labeled probes. The same experiments were negative for genomic DNA. These results, the low level of the stable Hb Costa Rica (5-6%), and the unequal distribution of the variant over the red cells are explained by assuming a somatic mosaicism as the genetic basis of the occurrence of this variant.

REFERENCES
1.		Rodriguez Romero, W.E., Castillo, M., Chaves, M.A., Saenz, G.F., Gu, L-H., Wilson, J.B., Baysal, E., Smetanina, N.S., Leonova, J.Ye., and Huisman, T.H.J.: Hum. Genet., 97:829, 1996.
2.		Smetanina, N.S., Gu, L-H., Rodriguez Romero, W.E., Howard, E.F., and Huisman, T.H.J.: Hemoglobin, 20:199, 1996.

---

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.