We have outlined a fast, non-radioactive strategy to identify point mutations in the 5' flanking region of the gamma-globin genes using denaturing gradient gel electrophoresis (DGGE) of amplified DNA. In a sample of previously characterized carriers of non deletion-type hereditary persistence of fetal haemoglobin (HPFH) the different point mutations in both gamma gene promoters could be easily identified by DGGE of a 327 bp fragment. A 4 bp deletion at position -225 to -222 of the A gamma globin gene was unexpectedly found in several samples and shown to represent a frequent polymorphism. Analysis of a 681 bp fragment specific for the 5' region of the A gamma gene, showed that this can be used to determine the haplotype of the chromosome under study. This technique may be useful in the study of sequence variations associated with high Hb F expression in physiological and pathological conditions.