PCDH9 and diabetes mellitus: When these protein-coding genes were examined, we found that the frequencies of AT genotype of the ALDH1L1 gene (rs1868138), the AG genotype of LY6D gene (rs184518892) and the GT genotype of PCDH9 gene (rs117681509) were significantly higher among DKD patients compared to DM patients (p < 0.001; Chi-square test; Fig. 2c).