Analysis of gDNA by SSCP. Genomic DNA was isolated from the peripheral blood mononuclear cells of patients and control subjects. The PCR was used to amplify individual exons of the β-spectrin gene for further analysis by SSCP. Shown are selected SSCP films pertaining to the exons of interest from the six patients who were ultimately found to have frameshift and nonsense mutations of the β-spectrin gene. Note the abnormal migration of additional bands in the patients (arrows), suggesting the presence of a mutation within one of the two alleles.