Figure 2. Five genotypes of Direct sequencing map for rs2250889 in MMP9 are shown. The single base directed with a black arrowhead was the SNP site rs2250889. The two bases collected in the black frame were two single nucleotide polymorphisms. The single base before site rs2250889 was a new SNP found in our research, and it was a linkage mutation, which did not change amino acid coding. Genotypes of rs2250889 in A, B, C, D, and E were separately C/G, G/G, C/G, C/C, G/G, while genotypes of the single base before it in A, B, C, D, and E were separately A/C, A/C, C/C, C/C, C/C.