Detection of the (–SEA) double α‐globin gene deletion by a simple immunologic assay for embryonic ζ‐globin chains Journal Articles uri icon

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abstract

  • AbstractHomozygous α‐thalassemia [α‐thal‐1], with loss of all four α‐globin genes, causes lethal hydrops fetalis. The most common mutation producing this syndrome is the Southeast Asian (–SEA) double α‐globin gene deletion. Erythrocytes from adults heterozygous for the (–SEA) deletion have minute amounts of embryonic ζ‐globin chains detectable by anti‐ζ‐globin monoclonal antibodies.Among 225 peripheral blood samples tested by a simple anti‐ζ‐immunobinding tetra‐zolium dye test, 81 were positive and 144 were negative. The majority of subjects were of Filipino, Chinese, or Laotian ancestry. All 81 positive samples were confirmed by Bam HI digests and a ζ‐cDNA probe to have the (–SEA) mutation. The (–SEA) double α‐deletion was the only abnormality in 58. In the others, it was combined with α‐globin or β‐globin mutations, or coincidental iron deficiency. Four other samples from (–SEA) heterozygotes were negative by this immunologic assay.Anti‐ζ negative samples included 78 deletions of the total α‐globin region, (–Tot), 23 single α‐globin deletions, and a variety of β‐globin mutations; 16 normocytic samples with normal α‐genes were also negative. Ten anti‐ζ positive and 25 anti‐ζ negative samples had benign triplicated ζ‐globin genes.In this population, the sensitivity of this test was 95%; and specificity for the (–SEA) mutation was 100%. Anti‐ζ immunobinding testing provides rapid, simple, and reliable screening for the (–SEA) double α‐globin deletion, although it does not detect the (–Tot) total α‐deletions. © 1993 Wiley‐Liss, Inc.

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publication date

  • September 1993