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Newborn Screening ACT Sheet

Sickle Cell Carrier (HbAS)

Differential Diagnosis: The hemoglobins are listed in order of the amount of hemoglobin present (F>A>S). This result is different from FS which is consistent with sickle cell anemia or sickle cell beta zero thalassemia (HbS B0), or FSA which is consistent with sickle beta-plus thalassemia.

Condition Description: Generally benign genetic carrier state (trait) characterized by the presence of fetal hemoglobin (F), and hemoglobin A and S.


  • Contact the family to inform them of the screening result to offer education and reassurance that infants and young children do not have clinical problems related to the carrier state for hemoglobin S.
  • Repeat screen or confirm result by alternate assay.
  • Order hemoglobin profile analysis (usually performed by electrophoresis).
  • Offer family members referral for hemoglobin disorder testing and genetic counseling.
  • Report findings to state newborn screening program.

Diagnostic Evaluation:

Hemoglobin separation by electrophoresis, isoelectric focusing or high performance liquid chromatography (HPLC) shows FAS. DNA studies may be used to confirm genotype. Sickledex is not adequate for confirmation of the diagnosis.

Clinical Considerations:

Newborn infants are usually normal. Prognosis is good, with a normal life expectancy. Carriers are at risk for having children affected by sickle cell disease. Older children and adults may have hematuria. Splenic infarction and an increased risk of sudden death associated with severe hypoxia, extreme physical exertion and dehydration have been reported.

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