PRENATAL-DIAGNOSIS OF BETA-THALASSEMIAS BY AMNIOCENTESIS - LINKAGE ANALYSIS USING MULTIPLE POLYMORPHIC RESTRICTION ENDONUCLEASE SITES

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  • 1 January 1980
    • journal article
    • research article
    • Vol. 56  (5) , 926-930
Abstract
To assess the applicability of multiple restriction endonuclease analyses of amniocyte DNA to the prenatal diagnosis of .beta.-thalassemias in general, 12 consecutive couples at risk were studied. DNA of both members of the 12 couples and a previous offspring of each was analyzed for the presence of 4 polymorphic restriction endonuclease sites: the Hpa I site 3'' to the .beta.-globin gene, HindIII site in the G.gamma. gene, the HindIII site in the A.gamma. gene, and the BamHI site 3'' to the .beta.-gene. Linkage disequilibrium between these sites and .beta.A or .beta.thal genes was not found, presumably due to the heterogeneity of .beta.thal genes. The high frequency of polymorphism at these sites allowed differentiation of .beta.A-bearing chromosomes from .beta.thal or .beta.S-bearing chromosomes in both members of 6 couples. In these couples, complete prenatal diagnosis by linkage analysis of amniocyte DNA would be possible. In the remaining 6 couples, .beta.A and .beta.thal chromosomes could be discriminated in 1 member. In about 50% of the pregnancies of these couples, exclusion of .beta.-thalassemia is possible by this analysis. When linkage analysis of polymorphic restriction endonuclease sites is carried out, prenatal diagnosis of .beta.-thalassemia states can be accomplished by amniocentesis alone in 75% of pregnancies at risk.