Abstract: Objective To evaluate discriminatory analysis on source identification of gastric cancer tissue based on the number of matched STR locus or identical allele. Methods Twenty two pairs of fresh gastric cancer tissue and homologous normal tissue were genotyped with Identifilerkit. Frequencies of STR genotypic alteration(STRGA),the number of matched STR locus without identical allele(A0),with 1 identical allele(A1),or with 2 identical alleles(A2) and the number of total identical alleles(IAn) were calculated with counting method. A1,A2 and IAn were evaluated with Fisher discriminant functions to determine the source of each gastric cancer tissue. Effectiveness of the identification of gastric cancer tissue was evaluated with error rate. Results The total frequency STRGA was 3.03%(95% CI:1.46%-4.88%). There were 31.38%(95% CI:13.86%-54.87%) of gastric cancer samples carried at least one STR locus with STRGA. It was confirmed by the Fisher discriminant functions that each of the 22 gastric cancer tissue samples came from its homologous normal tissue with an error rate of 0.00%. Conclusion Frequency of STRGA in gastric cancer tissue was high. Fisher discriminant functions based on the number of identical alleles or matched STR loci could be a feasible method for source identification of body for gastric cancer tissue samples.

Key words: forensic genetics, stomach neoplasms, discriminant analysis, matched locus, identical allele, personal identification