Abstract: Objective To investigate the single nucleotide polymorphism of NOS1AP gene with sudden unexpected death （SUD） during daily activities. Methods  The heart blood samples were collected from 60 SUD cases in normal daily activities as SUD group and the peripheral blood samples from 80 random unrelated cases as control group. The genome DNAs from all cases were isolated and the gene sequences were analyzed from specific primers of some SNP （rs10494366, rs10918859, rs12143842, rs12742393, rs3751284, and rs348624） of NOS1AP. The allele frequency and genotype frequency were calculated and the difference in these SNP between SUD group and control group were analyzed. Results The allele frequency and genotype frequency of rs3751284 which located at the sixth exon domain had significant statistical differences between the two groups （P<0.05）. The minor allele frequency of rs3751284 was 0.325 in SUD group and was 0.475 in control group. Conclusion rs3751284 might be a susceptibility locus for SUD.

Key words: forensic genetics, forensic pathology, polymorphism, single nucleotide, sudden unexpected death, NOS1AP gene