Thalassaemia-like carriers not linked to the beta-globin gene cluster.

This study describes the largest series reported to date, of individuals belonging to unrelated families carrying a beta-thalassaemia-like phenotype in whom the beta-globin gene was found to be structurally intact by sequence analysis. This genetic determinant appears haematologically heterogeneous, displaying either a silent beta-thalassaemia-like phenotype or a typical beta-thalassaemia carrier-like phenotype in different families. Compound heterozygosity for both beta-thalassaemia-like determinant and typical beta-thalassaemia allele resulted either in thalassaemia intermedia or thalassaemia major.