Rapid detection of point mutations and polymorphisms of the alpha-globin genes by DGGE and SSCA

We report the application of DGGE and SSCA for the identification of point mutations causing alpha-thalassemia. The alpha-globin genes were amplified in three overlapping fragments of 250 bp (I), 540 bp (II), and 600 bp (III), respectively. Fragments II and III were analysed by DGGE, while fragments I and II were analysed by SSCA. A panel of seven previously identified mutations was employed to test the combined DGGE/SSCA strategy: 5/5 and 6/7 mutations were detected by SSCA and DGGE, respectively. The same approach has also led to the identification of eight disease-causing mutations in a sample of 18 presumed non-deletional alpha-thalassemia carriers. During this pilot study, two novel mutations as well as three new polymorphisms were found. The combined application of SSCA and DGGE allows the rapid identification of mutations responsible for alpha-thalassemia and abnormal globin chain variants. Moreover, it will prove extremely useful for pre- and postnatal diagnosis and in screening programs for non-deletional alpha-thalassemias.