Prenatal diagnosis of beta-thalassemic mutations in Chinese by multiple restriction fragment-single strand conformation polymorphism analysis.

A modified approach of polymerase chain reaction (PCR)-based single strand conformation polymorphism (SSCP) has been developed for prenatal diagnosis of beta-thalassemic mutations. In this method, a single PCR product (1,350-bp) is first generated, which is then digested by restriction enzymes (BbsI, BamHI, DraI) to generate multiple shorter restriction fragments for electrophoretic analysis in an SSCP gel. The method is thus termed multiple restriction fragment (MRF)-SSCP. Two cases of chorionic samples and the blood samples of their parents were studied. The previously described amplification-created restriction site (ACRS) method was used to confirm the SSCP results obtained. Two polymorphic sites of the beta-globin gene which would influence the MRF-SSCP patterns are described, including a previously undescribed polymorphic site located at codon 3 (CAT or CAC) of the beta-globin gene.