With relatively recent advances in technology, detailed examination of DNA sequences has become possible. The hemoglobinopathies, which are inherited disorders resulting from changes in the globin genes, have been analyzed by several of these techniques. As the DNA within and surrounding the globin genes has been characterized, it has become possible to diagnose most pregnancies at risk for a hemoglobinopathy by analysis of fetal DNA. (9-15) This approach is especially valuable because fetal DNA can be isolated from amniocytes obtained by amniocentesis at 16-18 weeks of pregnancy, a much safer and far more widely practiced technique than fetoscopy or placental aspiration. Analysis of fetal DNA from cells obtained earlier in pregnancy would greatly improve the process of prenatal diagnosis for at-risk couples. The feasibility and safety of sampling by chorionic biopsy at about 8 to 10 weeks of pregnancy is currently being examined. (16, 17) Hemoglobinopathies, including the thalassemias, are recessively inherited conditions in which the parents of an affected child are usually only carriers and are thus free of the disease. Couples at risk are identified after either simple blood tests are performed or, all too often, after birth of an affected child. Carriers of thalassemia can be easily identified by the smaller than normal mean corpuscular volume of their red cells in the absence of iron deficiency; most carriers of β-thalassemia also have higher than normal levels of the minor adult hemoglobin, Hb A2 (α2 δ2). Carriers of sickle cell anemia can be detected by routine hemoglobin electrophoresis.
|Original language||English (US)|
|Number of pages||12|
|Journal||Annals of the New York Academy of Sciences|
|State||Published - 1985|
ASJC Scopus subject areas
- Biochemistry, Genetics and Molecular Biology(all)