ALLELOTYPE ANALYSIS OF ADENOCARCINOMA OF THE GASTRIC CARDIA

To identify chromosomal loci involved in the development of proximal g astric adenocarcinoma, this study delineated the pattern of allelic im balance in a series of 38 adenocarcinomas arising in the gastric cardi a. A total of 137 microsatellite markers covering all autosomal arms, excluding acrocentric arms, were analysed. A mean of 35 out of a total of 39 chromosomal arms studied were informative for each patient. The tumour group demonstrated a high level of allelic imbalance, with an observed median fractional allelic imbalance of 0.47 for the 29 intest inal-type adenocarcinomas and 0.54 for the nine diffuse-type adenocarc inomas. Allelic imbalance was detected in >50% of informative cases in both histological subtypes on a number of chromosomal arms. In the in testinal subtype, these included, 3p (61%), 4q (71%), 5q (59%), 8p (60 %), 9p (65%), 9q (83%), 12q (52%), 13q (52%), 17p (78%) and 18q (70%). A higher incidence of allelic imbalance was detected on chromosome 16 q in tumours of the diffuse type relative to those of the intestinal t ype. A more detailed mapping on chromosomes 4q and 6q identified a num ber of cases with subchromosomal breakpoints. In conclusion, this anal ysis has indicated regions of the genome potentially involved in the d evelopment of proximal gastric carcinomas.