Hemoglobin chain recombination and the pattern of composition of hemoglobin S and D in heterozygotes

The pattern of composition of hemoglobin in different heterozygotes for S and D hemoglobins is quantitatively accounted for by the relative rates of combination of the different chains alpha + beta A greater than alpha + beta D greatern than alpha + beta S greater than alpha + gamma. It is suggested that the recombination step may be one of the rate-limiting steps in hemoglobin assembly.