Compound heterozygosity for a β{ring operator}-thalassemia (frameshift codons 38/39; -C) and a nondeletional swiss type of HPFH (A→C at NT -110, Gγ) in a Czechoslovakian family

We have analyzed the levels and composition of the fetal hemoglobin (Hb F) in several members of a Czechoslovakian family with a heterozygosity for a newly discovered β{ring operator}-thalassemia (codons 38/39; -C), or for a newly detected nondeletional hereditary persistence of fetal hemoglobin (a form of Swiss-HPFH with an A→C mutation at nucleotide -100 5′ to the Cap site of Gγ), or with a compound heterozygosity for these two conditions. The Hb F level in the β{ring operator}-thalassemia heterozygotes averaged ∼ 0.3% with low Gγ values (∼ 28%) and relatively high AγT values (∼ 50%), that in the two Swiss-HPFH heterozygotes averaged 0.8% with ∼95% Gγ, while that of the compound heterozygote was 3.1% with ∼ 95% Gγ. The low Hb F levels were determined with a recently published cation exchange high-performance liquid chromatography (HPLC) procedure that is accurate at the 0.1%-0.2% Hb F level [3]. This method, together with a reversed-phase HPLC procedure, made it possible to detect this unusual type of nondeletional Gγ-HPFH and provided the data indicating that the increased Hb F in the compound heterozygote was derived mainly from the chromosome with the HPFH determinant.