sickle cell anemia

  • A medical student is working with you in clinic. He is preparing to see a 2-month-old infant whose older sister has sickle cell disease. The infant’s medical record has the results of the state newborn screen, which shows the hemoglobin fractionation to be an F, A, S pattern.
    Of the following, the MOST appropriate counseling for the family of this patient is that the infant

  • A. has a less severe phenotype of sickle cell disease
    B. has the most common form of sickle cell disease
    C. has sickle cell trait
    D. must be referred to a hematologist immediately
    E. must be retested at 4 to 6 months of age for a definitive diagnosis
  • The newborn described in this vignette has a hemoglobin fractionation pattern consistent with sickle cell trait. The result of the hemoglobin fractionation on newborn screen reflects the relative expression of hemoglobin types present from greatest to least. Therefore, an FAS pattern indicates that the hemoglobin with the highest expression is F hemoglobin, followed by A hemoglobin, and then S hemoglobin. All newborns, even those with hemoglobinopathies, will have a predominance of F hemoglobin at birth. A newborn with sickle cell disease would have S hemoglobin as the next most abundant hemoglobin type and therefore would have a pattern such as FS, FSA, or FSC. An infant with the most common type of sickle cell anemia (ie, SS disease) would have an FS pattern on a newborn screen, indicating that there is no production of hemoglobin A. The types of sickle cell disease associated with a milder phenotype are SC disease (newborn screen pattern FSC) and S β+-thalassemia (newborn screen pattern FSA), in which patients may have mild or no anemia. The families, and eventually the patient, should be counseled on the autosomal recessive inheritance pattern of sickle cell disease and the possibility of double heterozygous states that can also lead to disease (eg, SC disease, S β-thalassemia). The family should be offered genetic counseling if considering future pregnancies.
  • The US Preventive Services Task Force recommends that infants found to have sickle cell anemia receive prophylactic penicillin (125 mg by mouth twice daily) by 2 months of age and receive pneumococcal vaccines at recommended intervals. Most states use either thin-layer isoelectric focusing or high-performance liquid chromatography as the initial screening test, both of which have extremely high sensitivity and specificity for sickle cell anemia. Repeat testing at 6 months of age is not necessary in a patient whose newborn screen pattern is consistent with sickle cell trait. Patients with sickle cell trait are generally asymptomatic, with normal hematologic values and a normal life span; therefore, immediate referral to a hematologist is not indicated. There is emerging literature that patients with sickle cell trait may be more susceptible than those without sickle cell trait to rhabdomyolysis after extreme physical exertion, hyphema and glaucoma after eye trauma, renal dysfunction, and thrombosis; however, these associations are not yet definitive. This controversy has led to discrimination and prevention of participation among athletes and military personnel who have sickle cell trait. For these reasons, referral to a hematologist may be warranted at the family’s request but is not mandatory.

About Dr. Jayaprakash

Asst. Prof. of Pediatrics, ICH. Institute of Child Health. Gov. Medical College Kottayam. Kerala, India.

One Comment

  1. Manisha Harikumar

    Thank You Sir

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