AIM:To explore precise deleted regions and screen the candidate tumor suppressor genes related to sporadic colorectal carcinoma.METHODS:Six markers on 1q31.1-32.1 were chosen.These polymorphic microsatellite markers in 83 colorectal cancer patients tumor and normal DNA were analyzed via PCR.PCR products were electrophoresed on an ABI 377 DNA sequencer.Genescan 3.1 and Genotype 2.1 software were used for Loss of heterozygosity(LOH)scanning and analysis.Comparison between LOH frequency and clinicopathological factors was performed by x2 test.RESULTS:1q31.1-32.1 exhibited higher LOH frequency in colorectal carcinoma.The average LOH frequency of 1q31.1-32.1 was 23.0%,with the highest frequency of 36.7% (18/49) at D1S2622,and the lowest of 16.4%(11/67) at D1S412,respectively.A minimal region of frequent deletion was located within a 2 cM genomic segment at D1S413-D1S2622 (1q31.3-32.1).There was no significant association between LOH of each marker on 1q31.1-32.1 and the clinicopathological data (patient sex,age,tumor size,growth pattern or Dukes stage),which indicated that on 1q31.1-32.1,LOH was a common phenomenon in all kinds of sporadic colorectal carcinoma.CONCLUSION:Through our refined deletion mapping,the critical and precise deleted region was located within 2 cM chromosomal segment encompassing 2 loci (D1S413,D1S2622).No significant association was found between LOH and clinicopathologic features in 1q31.1-32.1.