Quantities of alpha Q chain variants in heterozygotes with and without a concomitant beta-thalassemia trait.
We have analyzed the quantities of alpha x chain-containing hemoglobins (alpha 2 x beta 2 and alpha 2 x delta 2) in 14 heterozygotes for Hb Q-India [alpha 64(E13)Asp-->His] or Hb Q-Thailand [alpha 74(EF3)Asp-->His]; both amino acid replacements are the result of mutations in the alpha 1-globin gene. Five of these persons (three with Hb Q-India and two with Hb Q-Thailand) had an additional beta(0)-thalassemia heterozygosity. The average quantities for Hb Q + Hb Q2 in the four groups were 17.2% (alpha alpha Q/alpha alpha; beta A/beta A), 9.5% (alpha alpha Q/alpha alpha; beta A/beta(0) Th), 26.8% (-alpha Q/alpha alpha; beta A/beta A), and 16.95% (-alpha Q/alpha alpha; beta A/beta(0) Th). These variations can best be explained by a posttranslational control mechanism; an imbalance in the alpha A, alpha Q, and beta A chain ratio will favor the alpha 2 Q beta 2 formation when an alpha-thalassemia is present and will reduce its formation in the presence of a beta-thalassemia heterozygosity.
Qin
W B
WB
Department of Biochemistry and Molecular Biology, Medical College of Georgia, Augusta 30912-2100.
Baysal
E
E
Wong
K F
KF
Molchanova
T P
TP
Pobedimskaya
D D
DD
Sharma
S
S
Wilson
J B
JB
Huisman
T H
TH
D000293:Adolescent; D000328:Adult; D002170:Canada; D002681:China; D003062:Codon; D005260:Female; D005914:Globins / Q000235:genetics*; D006455:Hemoglobins, Abnormal / Q000378:metabolism; D006579:Heterozygote; D006801:Humans; D007194:India / Q000208:ethnology; D008297:Male; D008875:Middle Aged; D009154:Mutation; D013019:South Africa; D017086:beta-Thalassemia / Q000097:blood* / Q000235:genetics
D003062:Codon; D006455:Hemoglobins, Abnormal; C049214:hemoglobin Q Thailand; C048600:hemoglobin Q India; D005914:Globins