Thalassemia screening
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
Overview
Screening
A screening policy exists on both sides of the island of Cyprus to reduce the incidence of thalassemia, which since the program's implementation in the 1970s (which also includes pre-natal screening and abortion) has reduced the number of children born with the hereditary blood disease from 1 out of every 158 births to almost zero.[1]
Methodology of Detection
- Polymerase chain reaction (PCR): The preferred method of thalassemia screening is PCR amplification of DNA from fetal trophoblastic tissue or amniotic fluid. Amniotic fluid is obtained from amniocentesis or from chorionic villus sampling.[2] If a newborn has the mutant globin chain within its germline DNA, PCR will amplify this DNA and will the mutation will be readily detectable.
- Risks: There is a risk for false negative testing, in which a patient truly has thalassemia but no mutant PCR product is amplified. Maternal DNA contamination can also a false negative test result. In order to bypass the possibility of false negatives, multiple confirmatory tests can be done, including the amplification refractory mutation system and reverse oligonucleotide hybridization.[2]
- Benefits: The advantages of PCR are the high sensitivity and low cost of the test.
- Hemoglobin electrophoresis: Analysis of globin gene products on gel electrophoresis can help make a diagnosis of thalassemia.[2]