BETA-O THALASSEMIA, A NONSENSE MUTATION IN MAN

The authors determined the complete nucleotide sequence of the 5' noncoding region and the first 74 amino acids of the nonfunctional β-globin mRNA in a patient with homozygous β0 thalassemia. They identified the molecular defect as a single nuclotide substitution in the coding region of the mRNA. At the position corresponding to amino acid 17, replacement of an adenine by a uracil changes the triplet AAG, which codes for lysine in the normal β chain, to an amber termination codon, UAG. This type of β0 thalassemia represents an example of a nonsense mutation in man.