Cytogenetic alterations affecting the chromosomal region 1p36 in FL with a predominantly diffuse growth pattern. G-banded pairs of chromosome 1 (cases 1 and 4, see Table 3) with structural alterations affecting the short arm (A). Representative FISH results on isolated nuclei from paraffin-embedded tumor tissue are shown for when the BAC probe RP4-755G5 for the chromosomal region 1p36 (red signal) and the YAC probe 968g8 for the region 1p22 (green signal) are used. Loss of genetic material in 1p36 is evident, whereas 2 copies of the region 1p22 are retained (B).