Detailed deletion mapping on chromosome region 9p21 in human periampullary neoplasms

Objective To further define the extent of chromosome 9p21 deletion in periampullary neopla sms.Methods The loss of heterozygosity at 5 microsatellite polymorphic markers on chromosome 9p21 was detected by polymerase chain reaction (PCR), polyacrylamide gel electr ophoresis (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 D 9S942 (28.6%), and some showing consecutive allelic loss. Sixty-two point fiv e percent (5/8) of ampullary carcinoma cases showed loss of heterozygosity at on e 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 o bserved in 14.2% (1/7) of insulinoma.Conclusion The minimal common region of chromosome deletion in periampullary neoplasms is d efined between the D9S974 and D9S942 loci within a 15 kb interval in 9p21, sugg esting the involvement of a novel tumor suppressor gene in their carcinogenesis .