We have studied three Brazilian kindreds presenting spectrin alpha I/74 hereditary elliptocytosis (HE) due to a G-->A substitution, responsible for the R28H mutation. The mutant allele was associated with alpha I domain haplotype 1 (XbaI(-)/MspI(-)/PvuII(+)) in all three families and with two different alpha II domain haplotypes (1/RIT, 4/RVR). This result may reflect that this mutation occurs in a "hot spot" and may have arisen more than once or that a crossing over event may have occurred between the two domains studied. We detected one new haplotype in the aI domain (haplotype 3 - XbaI(+)/MspI(-)/PvuII(+)). The mutant allele was associated with the lack of the aII domain Alu insertion in all three cases. Allele alpha(LELY), detected by PCR and restriction enzyme digestion, was present in the heterozygous form in patient 1 (alpha(HE)/alpha(LELY)) and in the homozygous form in patients 2 and 3 (alpha(HE-LELY)/alpha(LELY)). If was found. to be associated with alpha II domain haplotypes 1 (RIT) and 4 (RVR) and with the presence and absence of the Alu insertion. This may have arisen through recombination events, since this polymorphism is located in the alpha IV-alpha V domain junction, which is far distant from the alpha II domain.6415358