Objective: To further define the extent of chromosome 9p21 deletion in periampullary neoplasms.
Methods: The loss of heterozygosity at 5 microsatellite polymorphic markers on chromosome 9p21 was detected by polymerase chain reaction (PCR), polyacrylamide gel electrophoresis (PAGE) and silver staining in 35 specimens of periampullary neoplasms and their matching blood samples.
Results: Fifty percent (4/8) of pancreatic cancer cases showed the loss of heterozygosity at one or more microsatellite loci, with the more frequent sites of D9S974 (37.5%) and D9S942 (28.6%), and some showing consecutive allelic loss. Sixty-two point five percent (5/8) of ampullary carcinoma cases showed loss of heterozygosity at one or more of the loci, frequent site of loss being D9S942 (42.9%) and the next most frequent being IFNA (37.5%) and D9S171 (37.5%). Loss of one locus was observed in 14.2% (1/7) of insulinoma.
Conclusion: The minimal common region of chromosome deletion in periampullary neoplasms is defined between the D9S974 and D9S942 loci within a 15 kb interval in 9p21, suggesting the involvement of a novel tumor suppressor gene in their carcinogenesis.