LOH analysis of normal (N), low-grade (LG), and progressed DLCL (HG) samples microdissected from 2 selected cases (cases no. 3 and 4). (A) Map location of polymorphic markers on chromosome 9p21. (B) Case no. 3 showing apparent retention of heterozygosity in the progressed DLCL samples (HG), indicating homozygous deletions at D9S1749 and D9S1752 flanked by LOH, indicated by loss of the lower allele at IFNA, and the upper allele at D9S171. (C) Case no. 4 showing LOH in the DLCL samples (HG), encompassing 3 markers, indicated by loss of the upper allele at D9S1749 and loss of the lower alleles at D9S1747 and D9S1748.