LOSS OF HETEROZYGOSITY AT CHROMOSOME 9P21 IN PRIMARY NEUROBLASTOMAS -EVIDENCE FOR 2 DELETED REGIONS

The genes responsible for the development of neuroblastoma following i n vivo deletion or mutation are largely unknown. We have performed los s of heterozygosity studies on a series of 24 Portuguese primary neuro blastomas using 6 polymorphic markers located at chromosome 9p21 spann ing the p16/MTS1/CDKN2, p15/MTS2/CDKN2B, and the interferon alpha and beta genes. Loss of heterozygosity was observed in 4 of the 24 tumors (17%), a somewhat lower percentage than a previous study that identifi ed patients by a mass screening program. A correlation was also observ ed between 9p21 LOH and 1p36 LOH in our group of tumors. Two distinct regions of 9p21 deletion were observed: one located in the region adja cent to the markers D9S162 and D9S1747 and a second located centromeri cally of the pi 6 gene near the D9S171 marker. The latter region is ex clusive of the pi 6 gene, This result suggests the presence of at leas t one other tumor suppressor gene at 9p21, apart from the pi 6 and p15 genes, which may be of importance to the development of neuroblastoma . (C) Elsevier Science Inc., 1997.