Therefore, the initially observed finding suggesting that a higher abundance of bacteria with the Bifidobacterium genus was likely not to reflect causality and, instead, reflect horizontal pleiotropy or a complex (potentially gene-environment) interaction between the genomic region surrounding the rs4988235 SNP (i.e., the LCT/MCM6 gene) with both Bifidobacterium abundance and CRC risk, as indicated by our colocalisation analyses. Here, MCM6 is linked to colorectal carcinoma.