Abstract: ObjectiveTo explore the effect of fatty acid desaturase (FADS) single nucleotide polymorphisms (SNPs) on erythrocyte membrane polyunsaturated fatty acids (PUFAs) composition and cognitive memory of school-age children. MethodsPrimary school students aged 8-12 years were selected from Pingtian Town, Nanxiong City to participate in the docosahexaenoic acid (DHA) supplementation randomized controlled trial. Basic information, dietary data, anthropometric measurements and fasting blood samples were collected. Cognitive function was assessed using digital span test and Wisconsin card sorting test. Erythrocyte membrane fatty acids composition was determined by gas chromatography. Genome DNA was extracted from blood clots and used to identify the genotypes of 4 FADS tag SNPs.ResultsA total of 106 school students from grade three to grade five were investigated, including 62 males and 44 females, with an average age of (9.17 ± 1.03) years. There was no significant difference in the cognitive memory function of DHA in different erythrocyte membrane (all P＞0.05). The four sites of FADS were in accordance with H-W equilibrium (0.409-0.970). The differences of FADS rs174561 genotypes in different C18∶2, C18∶3(n-6), C20∶5, total n-3, AA/LA, EPA/ALA were statistically significant (P < 0.01 or P < 0.05). The mixed linear model analysis showed that the scores of number of completed categories and conceptual level ,conceptual level for mm+Mm genotype were higher than those for MM genotype (all P＜0.05). The total number of errors and total error rate of mm+Mm genotype were lower than those of MM (all P＜0.05). ConclusionFADS SNPs can influence PUFAs status and cognitive function in school-age children.