Abstract： Objective To study the relationships between single nuchotide polymorphisms (SNP) of gene rash homebox-1(MSX-1)(rs3821949,rs12532)and sporadic tooth agenesis by filtering the susceptibility genes in a Jiangsu province population.Methods DNA samples were extracted from 198 patients with sporadic tooth agenesis and 207 control subjects.Two MSX-1 gene polymorphisms were genotypod using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) assay.The association between the genetic polymorphism and risk of sporadic tooth agenesis wag estimated by χ2 and logistic regression.The Phase wag used to determine the Hardy-Weinberg equilibrium and haplotype association.Results In the population,the allele frequency and genotype rates of the SNP rs3821949 were significant different between the patients with sporadic tooth agenesis and normal controls:the A allele frequency in the patients (43.2%) was significantly higher than that in the normal controls (31.4%,P=0.008),and the AA genotype rate ofthe patients (14.7%) was significantly higher than that of the controls (12.6%,P=0.030).However,There were no significant diffeFences in the allele frequency and genotype rates of the SNP rs12532 between the patients with sporadic tooth agenesis and normal control s.Similar results were obtained between the mandibular ineisor agenesis cases and controls.The haplotype frequencies of GA(27.9%)were significantly lower in non.mandibular incisor agenesis cases group than that in the control group(37.0%,P=0.03,OR=0.51).Conclusions The results show that SNP rs3821949,which is located at 5'near region of the MSX-1 gene,is likely to have an influence on the transcriptional activity of this gene and be associated with sporadic tooth agenesis.The haplotypes constructed with these 2 SNP sites may be linked with the susceptibility gene of non-mandibular incisor agenesis.