MMP9 and retinopathy of prematurity: There were no statistically significant associations between single variants or haplotypes of the MMP-9 or TIMP-2 gene and ROP; however, two and three loci interactions between MMP-1 rs1799750 and TIMP-1 rs4989 (p = 0.015), as well as MMP-1 rs1799750, MMP-9 rs17576 and TIMP-1 rs4989 (p = 0.0003), influencing the risk of ROP were observed.