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Hereditary persistence of fetal hemoglobin-beta-thalassemia syndrome
Hereditary persistence of fetal hemoglobin (HPFH) associated with beta-thalassemia (see this term) is characterized by high hemoglobin (Hb) F levels and an increased number of fetal-Hb-containing-cells.
Prevalence of this form is not known.
The association of HPFH with beta-thalassemia mitigates the clinical manifestations which vary from a normal state to beta-thalassemia intermedia (see this term).
HPFH is due to deletions in the beta-globin gene cluster or point mutations in the HBG1 and HBG2 genes (11p15.5).
Diagnosis is based on the presence of a significant elevation in HbF ranging from 10-40% in heterozygotes with normal or near normal red blood cell indices. HbF is homogeneously distributed among the erythrocytes and HbA2 is normal or reduced.
The distinction between HPFH and delta-beta-thalassemia (see this term) is subtle and should be confirmed by alpha-beta-globin chain synthesis ratio and DNA analysis since the distinction between these two conditions is not always possible from routine hematologic analyses.
HPFH transmission is co-dominant. Homozygosis for the non-deletional form has to date been reported in rare cases.