NOS2 and psoriasis: In our study, we observed a significant correlation between the severity of psoriasis and the interaction between genotypes and the abundance of Streptococcus genus on the skin, for the SNPs rs12445568, rs10782001, and rs12924903, all related to the FBXL19 gene, and for the SNPs rs2046068 (IL22), rs27432 (ERAP1), rs892085 (ILF3), and rs4795067 (NOS2).