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Sickle Cell Anemia

Why Test Came Back Negative

12/08/2010

Question:

My daughter was tested as an infant for sickle anemia and the test came back negative. Now she is twenty and she has been diagnosed with sickle cell anemia. Also grandaughter who is three diagnosed with chronic sickle cell anemia. Why would both test when infants come back negative?

Answer:

To test for Sickle Cell anemia, a blood test is done called a Hemoglobin Electrophoresis. This test will determine the type of hemoglobin a person has. This test is able to show differences between normal hemoglobin (Hb A), Sickle hemoglobin (Hb S), and other different kinds of hemoglobin (such as Hb C, Hb D, Hb E, etc.).

There are a few reasons why a test might have come back negative. There is another test called a solubility test (or SickleDex or sickle prep) which can look for sickle cell anemia due to changes in the hemoglobin genes – specifically HbS, which use to be done a lot. However, it is not as accurate as the Hemoglobin Electrophoresis test. So the test could have missed it. It could be that your daughter or granddaughter has a different type of hemoglobin disease that the SickleDex test did not look for if that was the type of test that was done. Finally, there is always human error and the laboratory made a mistake when they did the test.

Because sickle cell anemia is an autosomal recessive inherited disease - hopefully your daughter and /or your granddaughter’s parents have had a chance to talk to a genetic counseling or geneticist to talk about the inheritance of the disease. They might also be able to tell you why they had a negative test. They can locate a genetics center near them at the website below or check with their doctor for a referral. Also, the Sickle Cell Disease Association of America has lots of very good information.

Related Resources:

National Society of Genetic Counselors Resource Center
Sickle Cell Disease Association

For more information:

Go to the Sickle Cell Anemia health topic, where you can:

Response by:

Anne   Matthews, RN, PhD Anne Matthews, RN, PhD
Associate Professor of Genetics
School of Medicine
Case Western Reserve University