KIR2DL5 combined with the HLA-C1/C2 heterozygous genotype showed a protective effect (AS 5.97% vs. normal 11.66%; <i>p</i> = 0.002; <i>p<sub>FDR</sub></i> = 0.0127, OR, 0.48 95% CI: 0.33-0.70); in contrast, KIR 2DS4/1D combined with the HLA-C1C1 homozygous genotype (AS 45.33% vs. normal 35.92%; <i>p</i> = 0.002; <i>p<sub>FDR</sub></i> = 0.0127, OR, 1.48 95% CI: 1.21-1.81) represented a risk factor for AS development.
The results showed that the frequencies of KIR2DL1 and KIR2DL5 were significantly higher in the AS patient group than those in the control group (p = 0.012 and p = 0.009, respectively).
A similar increase was reported in the Thai population: KIR3DS1, KIR2DS5, and KIR2DL5 gene frequencies were higher in AS (p(c) < 0.05, p < 0.05, and p(c) < 0.05, respectively).