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Physiologic decline in fetal hemoglobin parameters in infants with sickle cell disease: implications for
1Duke Pediatric Sickle Cell Program, Department of Pediatrics, Duke University Medical Center, Durham, North Carolina 27710, USA.
Insights
Fetal hemoglobin (HbF) levels decline in infants with sickle cell disease, dropping below protective thresholds by age two. Early pharmacologic intervention to boost HbF may prevent organ damage in these children.
Area of Science:
- Hematology
- Pediatric Medicine
- Genetic Blood Disorders
Background:
- Fetal hemoglobin (HbF) is crucial for mitigating sickle cell disease severity.
- Understanding HbF's natural decline in infancy is key to managing sickle cell disease.
Purpose of the Study:
- To investigate the physiological decline of fetal hemoglobin (HbF) parameters in infants with sickle cell disease.
- To analyze HbF levels, F cell percentages, and HbF per F cell in infants with HbSS and HbSC genotypes.
Main Methods:
- Quantification of HbF percentage and F cells.
- Calculation of HbF per F cell.
- Analysis of 138 blood samples from 44 infants with HbSS and 56 samples from 24 infants with HbSC.
Main Results:
- Infants with HbSS showed a logarithmic decline in HbF parameters, reaching 14.6% HbF and 64.7% F cells at 24 months.
- HbF per F cell dropped below 15 pg/cell by 12 months in HbSS infants.
- HbSC infants experienced a faster decline, with HbF per F cell below 10 pg/cell by 12 months.
Conclusions:
- By age two, HbF parameters decrease to levels insufficient to prevent sickling in infants.
- Pharmacologic strategies to enhance HbF production in infancy should be considered to prevent chronic organ damage.
- Early intervention is critical for managing sickle cell disease progression.
Purpose:
Fetal hemoglobin (HbF) is an important determinant in the clinical severity of patients with sickle cell disease. The physiologic decline in HbF parameters in a cohort of infants with sickle cell disease was investigated.
Patients And Methods:
The percent HbF and F cells were quantitated, and the HbF per F cell was then calculated. One hundred thirty-eight blood samples from 44 infants with homozygous sickle cell anemia (HbSS) and 56 samples from 24 infants with sickle cell hemoglobin (HbSC) were studied.
Results:
Infants with HbSS had a logarithmic decline in HbF parameters; at 24 months, the average HbF was 14.6%+/-7.3% and the % F cells was 64.7%+/-16.9%. The amount of HbF in each F cell (HbF per F cell) was <15 pg/cell, a suggested threshold for intracellular sickle polymerization, by age 12 months. Infants with HbSC had a more rapid decline: at 12 months the average % HbF was 12.2%+/-9.3%, the % F cells was 60.5%+/-18.7%, and the HbF per F cell was <10 pg/cell.
Conclusions:
By age 2 years, HbF parameters including the % HbF, % F cells, and the HbF per F cell decrease to levels insufficient to inhibit sickling. Pharmacologic intervention designed to enhance HbF production and prevent chronic organ damage should be considered during infancy.