Diagnosis of thalassemia using cDNA amplification of circulating erythroid cell mRNA with the polymerase chain reaction

We have developed a technique to diagnose the α- and β-thalassemia (thal) syndromes using the polymerase chain reaction to amplify cDNA copies of circulating erythroid cell messenger RNA (mRNA) so as to quantitate the relative amounts of α-, β-, and γ-globulin mRNA contained therein. Quantitation, performed by scintillation counting of ³²P-dCTP incorporated into specific globin cDNA bands, showed ratios of α/β-globin mRNA greater than 10-fold and greater than fivefold increased in patients with β⁰- and β⁺-thal, respectively, as well as a relative increase in γ-globin mRNA levels. Conversely, patients with α-thalassemia showed a decreased ratio of α/β-globin mRNA proportional to the number of α-globin genes deleted. This methodology of ascertaining ratios of globin mRNA species provides a new, simplified approach toward the diagnosis of thalassemia syndromes, and may be of value in other studies of globin gene expression at the transcription level.