Genetic analysis of BCL-65′ mutations in PCNSL by PCR-SSCP (A and B) and DNA direct sequencing (C and D). (A and B): Representative results obtained for PCR products E1.10 (A) and E1.11 (B) are shown. Samples of PCNSL are indicated at the top of each lane by a numbered code. A positive control (POS), represented by a tumor sample known to harborBCL-6 5′ mutations, as well as a normal (N) sample, represented by a lymphoblastoid cell line, are also included for each PCR-SSCP fragment shown. Samples were scored positive when their migration pattern differed from the normal control and the migration abnormalities could not be ascribed to population polymorphisms. Among the PCNSL samples shown, cases scored as positive included cases 3, 14, and 11 (for PCR product E1.10); 8, 28, and 47 (for PCR product E1.11). (C and D): Nucleotide sequencing analyses of BCL-65′ mutations in PCNSL (cases 14, 43, and 47). The sequence of each PCNSL case is matched either to the sequence of a normal control (N) displaying germline BCL-6 alleles (D) or to the sequence of a PCNSL sample harboring mutations at a different site (C). The position of mutations is indicated by the nucleotide number of the corresponding BCL-6 germline sequence (the first nucleotide of the BCL-6 cDNA was arbitrarily chosen as position +1).