Hb G-Philadelphia alpha68(E17)Asn->Lys
ALSO KNOWN AS G-Knoxville; Stanleyville-I, D-Washington; D-St. Louis; G-Bristol; G-Azakouli; D-Baltimore
CONTACT External
HEMATOLOGY No hematological abnormalities in the heterozygote due to the presence of the Hb G-Philadelphia anomaly
ELECTROPHORESIS Hb X and Hb A separate at alkaline pH but not at acidic pH; moves to the position of Hb S on paper, starch gel, and cellulose acetate; excellent separation on IEF
CHROMATOGRAPHY Hb X separates from Hb A by both cation and anion exchange chromatography
STRUCTURE STUDIES Tryptic digestion; separation of peptides by fingerprinting or by cation exchange chromatography or by reversed phase HPLC; amino acid analysis
DNA ANALYSES Two mutations have been detected (Refs. 9,10); 1) AAC->AAG on a chromosome that carries the 3.7 kb deletion (-alpha3.7/ on the alpha2alpha1 hybrid gene); 2) AAC->AAA of the alpha2 gene of a chromosome with a normal complement of two alpha-globin genes (alphaGalpha/)
OCCURRENCE This is the most common alpha chain variant in Blacks; also present in Italians from Northern Italy and Sardinia, and in a few Chinese families
OTHER INFORMATION 1) Hb G-Philadelphia in Blacks is present on a chromosome with the 3.7 kb deletion (alpha-thal-2); the quantity of Hb G in such individuals varies between 30-35%. 2) When an alpha-thal-2 (3.7 kb deletion) occurs in trans (-alphaG/-alpha) the quantity of Hb G is increased to ~45%; these individuals have a distinct microcytosis and hypochromia (alpha-thal-2 homozygotes). 3) Homozygosity for Hb G-Philadelphia (-alphaG/-alphaG) results in 100% G-Philadelphia; these individ-uals also have a distinct microcytosis; hypochromia (alpha-thal-2 homozygotes). 4) Hb G-Philadelphia in combination with an alpha-thal-1, although extremely rare, results in an Hb H disease (-alphaG/--) and 100% G-Philadelphia. 5) The occurrence of Hb G-Philadelphia (-alphaG/alphaalpha) with Hb S and/or Hb C is rather common. 6) Italians with Hb G-Philadelphia have a full complement of four alpha-globin genes (alphaGalpha/alphaalpha) and 20-25% G-Philadelphia; no hematological abnormalities are found
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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.