MUC5AC and colorectal carcinoma: The increased resolution provided by whole community shotgun metagenomic sequencing may in part explain why a recent meta-analysis of 16S rRNA fecal microbiomes from CRC patients failed to find biomarkers of CRC,45 while subsequent shotgun sequencing meta-analyses detected increased protein and mucin catabolism genes and reduced carbohydrate degradation genes.46 Thus, we recommend that future studies consider using shotgun sequencing for their sample analysis.