Abnormal SSCP patterns are found in some pediatric T-cell leukemias. PCR-SSCP analysis of exon 3 (A) and the proximal promoter (B) of CD95. C, normal human genomic DNA amplified using a mutant primer with a single base mismatch (positive control);7,14,64, patient leukemias; N, peripheral blood from healthy controls. Abnormal migrating bands are seen in the positive controls, the leukemias and in one healthy control (*).