CRISPR/Cas9-mediated introduction of single nucleotide mutation was used to directly demonstrate that the presence of allele G led to higher levels of PCAT19 and CEACAM21 transcripts [91]; the genotype of rs11672691 was successfully converted from G/A to G/G or A/A in prostate cancer cell line 22Rv1. Here, CEACAM21 is linked to prostate cancer.