Detection of Sickle Cell βS-globin Allele by Hybridization with Synthetic Oligonucleotides

Two 19-base-long oligonucleotides were synthesized, one complementary to the normal human β -globin gene (βA) and one complementary to the sickle cell β -globin gene (βS). The nonadecanucleotides were radioactively labeled and used as probes in DNA hybridization. Under appropriate hybridization conditions, these probes can be used to distinguish the βSgene from the βSallele. The DNA from individuals homozygous for the normal β -globin gene (βAβA) only hybridized with the βAspecific probe; the DNA from those homozygous for the sickle cell β -globin gene (βSβS) only hybridized with the βSspecific probe. The DNA from heterozygous individuals (βAβS) hybridized with both probes. This allele-specific hybridization behavior of oligonucleotides provides a general method for diagnosis of any genetic disease which involves a point mutation in the DNA sequence of a single-copy gene.