MRNA analysis in reticulocytes of subjects with Hb D, Hb Porto Alegre, Hb E, and different types of unstable hemoglobin variants.
Using a reverse transcription-polymerase chain reaction (RT-PCR) technique we determined the alpha 2/alpha 1, alpha/beta, and gamma/beta mRNA ratios in reticulocytes of 11 patients with seven different unstable beta chain variants, of 4 patients with two unstable alpha chain variants, in hemoglobin (Hb) D, Hb Porto Alegre, and Hb E heterozygotes, and in 8 patients with Hb X-beta 0-thalassemia (thal) (three D-beta 0-thal, one Porto Alegre = beta 0-thal, one Lulu Island-beta 0-thal, and three E-beta 0-thal). In addition, we determined the beta X/beta A mRNA ratios (X = unstable) in some Hb D heterozygotes and in 6 subjects with an unstable beta chain variant. Normal alpha/beta and beta X/beta A mRNA ratios were found in all heterozygotes tested, indicating that the respective mutations did not alter the stability of the mRNAs. The alpha/beta mRNA ratio in four Hb E heterozygotes averaged 4.21 (normal, 4.47), and that in 2 patients with Hb E-beta 0-thal and four alpha-globin genes (alpha alpha/alpha alpha) averaged a high 22.4. The gamma mRNA level in the Hb E heterozygotes was < 1% but varied greatly in patients with Hb E-beta 0-thal; the alpha/(gamma + beta) mRNA ratios in the 2 patients were 15.5 and 16.7, respectively. The large differences in alpha/beta and alpha/(gamma + beta) mRNA ratios in reticulocytes of subjects with AE and with E-beta 0-thal may be due to differences in the levels of normally-spliced beta E and abnormally-spliced beta E mRNAs. Only the latter is unstable and is preferentially produced in bone marrow and reticulocytes of Hb E-beta 0-thal patients, where it is rapidly degraded.
Smetanina
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Department of Biochemistry and Molecular Biology, Medical College of Georgia, Augusta 30912-2100, USA.
Huisman
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D000293:Adolescent; D000328:Adult; D001483:Base Sequence; D002648:Child; D005260:Female; D005914:Globins / Q000235:genetics; D006446:Hemoglobin E / Q000235:genetics; D006455:Hemoglobins, Abnormal / Q000235:genetics*; D006801:Humans; D007223:Infant; D008297:Male; D008875:Middle Aged; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction; D012333:RNA, Messenger / Q000032:analysis* / Q000378:metabolism; D012156:Reticulocytes / Q000737:chemistry*
D006455:Hemoglobins, Abnormal; D012333:RNA, Messenger; C032001:hemoglobin D; D005914:Globins; D006446:Hemoglobin E; C034991:hemoglobin Porto Alegre