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Prenatal Diagnosis of the Hemoglobin Disorders by DNA Analysis *
Author(s) -
FUKUMAKI Yasuyuki
Publication year - 1985
Publication title -
congenital anomalies
Language(s) - English
Resource type - Journals
eISSN - 1741-4520
pISSN - 0914-3505
DOI - 10.1111/j.1741-4520.1985.tb00647.x
Subject(s) - restriction fragment length polymorphism , genetics , southern blot , biology , microbiology and biotechnology , prenatal diagnosis , gene cluster , thalassemia , gene , genomic dna , mutation , restriction site , nonsense mutation , restriction enzyme , polymerase chain reaction , fetus , missense mutation , pregnancy
Three types of approach to prenatal diagnosis by DNA analysis were described with drawing on examples from sickle cell anemia and thalassemias. The first approach is to detect the change of the restriction pattern of fetal DNA due to the mutation. One type of 6|3‐thalassemia mutation was detected by Southern blotting analysis of genomic DNA when probed with a radiolabeled globin gene because of a large deletion in the β‐globin gene cluster. Since the sickle mutation altered the recognition site of Mst II in the β‐globin gene, Southern blot of Mst II digest of DNA from a homozygote hybridized with a 1.15 kb Mst II 0‐globin gene sequence yielded autoradiograms with a 1.35 kb fragment instead of a normal 1.15 kb fragment. The second approach is based upon the feasibility of using synthetic oligonucleotide probes to detect single base mismatches. Two synthetic 19 nucleotide long oilgonucleotide probes, one complementary to the normal human 0‐globin gene sequence and one complementary to a β‐thalassemia gene sequence (a C‐T substitution at position 654 of IVS2) were used to distinguish between the normal and thalassemia genes in Bam HI digests of genomic DNAs. Linkage analysis using restriction fragment length polymorphisms (RFLPs) in the β‐globin gene cluster provides the third approach to prenatal diagnosis by DNA analysis. Allele‐linked RFLPs are only available for detection of the sickle mutation and one type of nonsense mutation of β‐thalassemia in limited populations. Familial‐linked RFLPs have been used for prenatal diagnosis of β‐thalassemias because 17 polymorphic restriction enzyme cleavage sites were identified in the β‐globin gene cluster. This approach is also applicable to prenatal diagnosis of genetic disorders in which the gene products responsible for pathogenesis have not been identified. However, a possibility of diagnosis by this approach depends on RFLPs of parents. Further technical development to simplify the DNA analysis will facilitate clinical use of DNA analysis in prenatal diagnosis.