Nonsense and frameshift mutations in beta 0-thalassemia detected in cloned beta-globin genes.

The molecular basis for deficiency of beta-globin synthesis in beta-thalassemia was investigated by gene cloning and DNA sequencing. beta-Globin genes of two patients with beta 0-thalassemia were cloned in a phage lambda vector. Both beta-genes transcribed normally in vitro. The gene of an Italian individual had a single nucleotide substitution (C leads to T) in the codon for amino acid 39 that resulted in formation of a nonsense codon. In a Turkish individual, the cloned beta-globin gene had a dinucleotide deletion in the codon for amino acid 8. This frameshift mutation produced a termination codon at the position of the new 21st codon. Mutations that lead to premature termination of beta-globin synthesis appear to be among the common causes of beta 0-thalassemia in man.