As expected the most frequent homozygous deletions occurred at 9p21, in a 4 Mb segment that consistently included CDKN2A and CDKN2B. The observed frequency of CDKN2A homozygous deletions reached 32%, which is close to the frequency found by Q-PCR of micro dissected tumor biopsies [43]. The gene discussed is CDKN2A; the disease is neoplasm.