Introduction: Newborn screening for hemoglobinopathies is occurring in many locations in the United States. Commonly, liquid cord blood may be screened with either cellulose acetate (CAC) or isoelectric focusing (IEF) electrophoresis. The presence of hemoglobin Bart's (γ4), has been correlated with α-thalassemia, as defined by restriction fragment analysis. However, there are no data in the literature correlating the sensitivity of these two electrophoretic methods with the detection of thalassemic genotype. Methods: Random samples of liquid cord blood were collected initially, based on the presence of hemoglobin Bart's on CAC and then compared with detection by IEF. A second set of samples was then chosen based on the absence of hemoglobin Bart's on CAC. IEF was also performed. Restriction analysis of all samples was performed to determine α-thalassemia or normal genotype. A total of 72 samples was analyzed. Results: All patients with hemoglobin Bart's on CAC had Bart's detectable by IEF (n = 21). Eighteen of these samples were consistent for homozygous α-thal-2, whereas three showed a heterozygous α-thal-2 haplotype. In the second set of 51 samples without hemoglobin Bart's on CAC, four samples were detected by IEF to have hemoglobin Bart's. Among 47 samples without hemoglobin Bart's by either method, ten were heterozygous for α-thal-2 haplotype, and the remaining 37 samples were normal. Discussion: Our data indicate that CAC and IEF are both accurate in the detection of hemoglobin Bart's in persons who are α-thal-2 homozygous. For α-thal-2 heterozygous haplotype, IEF is more sensitive in determining the presence of hemoglobin Bart's than CAC. However, neither method will detect the majority of this haplotype. We suggest more sophisticated molecular analysis for detection of α-thal-2 heterozygous genotype in at-risk populations.
- Newborn screening
ASJC Scopus subject areas
- Pediatrics, Perinatology, and Child Health