In a series of 46 glioblastomas, 16 anaplastic astrocytomas and eight astrocytomas, all tumours retaining one or both alleles of CDKN2A (48 tumours) and CDKN2B (49 tumours) were subjected to sequence analysis (entire coding region and splice acceptor and donor sites). The gene discussed is CDKN2B; the disease is astrocytoma (excluding glioblastoma).