Abstract: ObjectiveTo define the minimally lost regions(MLR) on chromosome 1q, and further to explore the molecular genetics alteration during the malignant progression of human colon mucosa. MethodsFifteen microsatellite markers were used and combined with PCR to detect the frequencies of LOH of every selected microsatellite site on chromosome 1q in colon carcinoma. Results Chromosome 1q LOH was identified in 69 of 93 colon carcinoma (74.2%). The LOH values in the D1S413 (34.62%) and D1S305 (43.75) were higher than that in other microsatellite markers. Through analyzing allelic loss mapping on chromosome 1q in colon carcinoma, we found that the common lost regions are between D1S2878~D1S2346(1q21.3~1q23.2) as well as D1S413~D1S249(1q31.3 ~1q32.1). The MLR was in D1S249~D1S413, which was about 7.1cM. A significant association was found between chromosome 1q LOH and histopathological grade, and the frequencies of LOH is the highest in poor differentiated colon carcinoma(P<0.05). ConclusionThere are high LOH frequency on the chromosome 1q31.3 ~1q32.1 and 1q21.3~1q23.2 in colon carcinoma. The result suggests these regions perhaps harbor putative tumor suppressor gene(s) contributing to tumorigenesis and differentiation in human colon carcinoma. The high frequency allelic loss on 1q is associated with colon carcinoma cell differentiation.