Structure of human hemoglobin messenger RNA and its relation to hemoglobinopathies.

1. One-fifth to 1/4 of globin mRNA is untranslated sequence other than polyadenylic acid. 2. The untranslated sequences of mRNA vary markedly in their sequence and in their length. 3. Globin mRNAs demonstrate a marked bias in codon selection. 4. Viral mRNA shows a quite different pattern of codon selection; therefore, the selection of codons is not uniform for all mRNAs functioning in animal cells. 5. Elongated hemoglobin chains can be accounted for by frame-shift mutations, or point mutations within the normal termination codon. The additional amino acids are then coded for by sequences that are normally untranslated. 6. Certain hemoglobin deletion mutants occur at sites where there are partially reiterated sequences within the heomoglobin messenger RNA.