Mild β + (−87)‐thalassemia CACCC box mutation is associated with elevated fetal hemoglobin expression in cis

The β°‐thalassemia codon 39 nonsense mutation predominant in Sardinia is severe, and homozygotes are transfusion dependent. Two‐thirds of β° 39 alleles are linked to A γ T (haplotype II). Onefourth are linked to A γ I (haplotypes I and IX), as is the mild β + ‐thalassemia −87 C→G mutation (haplotype VIII). β + /β°‐Thalassemla VIII/II compound heterozygotes have Significantly higher A γ I : A γ T (23:7) than β°‐thalassemia I/II (24:20) or IX/II (16:17) cases. This suggests that the β + −87 mutation is associated with elevated γ expression in cis, which may contribute to the lack of transfusion‐dependence in β + /β° Cases. © 1994 Wiley‐Liss, Inc.