FISH results for BCL9 probes. (A) Localization of PAC containing BCL9 sequences to chromosome 1q21 on normal metaphases. (B) Rearrangement of CEPH YAC 882B3 in case no. 2 with t(1;22)(q21;q11), showing hybridization signals at the breakpoints of both der(1) and der(22) chromosomes. (C) Metaphase of case no. 7 showing YAC 882B3 hybridization signals on normal 1 and der(19) chromosomes. Amplification of hybridization signal on the add(1) is shown by a solid arrow. Note the extra unidentified material between centromere and YAC signal.