Objective To study molecular genetics mechanism of tongue coating formation in patients with primary gastric cancer. Methods Regarded primary gastric cancer as basic disease. Based on 387 cases of primary gastric cancer patients and 392 cases of normal control subjects

the researchers recorded tongue coating colour and nature including white

yellow and others in color and thin

thick and exfoliated in nature. The researchers used ligase detection reaction to detect distribution of eight single nucleotide polymorphic（ SNP） site of transforming growth factor-α（ TGF-α） gene in peripheral venous blood to analyze correlation between coating colour and nature with SNP site of TGF-α gene. Results There was no statistically difference in distribution of coating color between normal control people and primary gastric cancer patients carried with only SNP rs11466285 TC / TT genotype（ P = 0. 122）

but there was statistically difference in distribution of coating colour and tongue nature between normal control people and those patients with other various genotypes（ P < 0. 01）. SNP rs503314 GG genotype

rs3732253 TC / TT genotype and rs538118

rs2166975 significantly influenced changes of tongue coating color（ P < 0. 05）

while SNP rs503314 GC /CC genotype and rs538118 significantly influenced changes of tongue nature（ P < 0. 05）. Conclusion The formation of tongue coating of primary gastric cancer patients may be associated with polymorphism of TGF-α gene.