Two novel beta-thalassemia mutations are described. The first mutation, found in an Italian family, is a G----A substitution in nucleotide (nt) +22 relative to the beta-globin gene Cap site. This mutation creates a cryptic ATG initiation codon, the utilization of which for translation would result in premature termination 36 bp 3′ downstream. The second mutation, found in an Irish family, is a T----C substitution in nt +1570, or 12 bp 5′ upstream of the AATAAA polyadenylation signal in the 3′ noncoding region. It is postulated that this mutation leads to destabilization of the encoded beta-globin mRNA.

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