We performed transcriptome-wide Mendelian randomization analyses (MR), which, under certain assumptions, can provide causal estimates,9 to identify genes that may play a role in CRC development based on single-cell transcriptomic data generated previously from CD4+ T cells.8 We then performed genetic colocalisation to evaluate possible misinference due to linkage disequilibrium and add robustness to our results. Here, CD4 is linked to colorectal carcinoma.