The MLH1 V384D polymorphism has been associated with cancer risk in some tumor types. In addition, according to one report, MLH1 V384D polymorphism has been reported to be associated with primary resistance to EGFR-TKIs in patients with EGFR L858R-positive lung adenocarcinoma and may potentially be a novel biomarker to guide treatment decisions for those patients. The effect of this MLH1 polymorphism when present with other EGFR-TKI sensitizing mutations such as Exon 19 deletions in EGFR remains to be clarified. Some studies have shown that patients carrying the MLH1 V384D variant have an increased risk of the development of microsatellite-instable as well as -stable colorectal cancer. This variant has an allele frequency of 4% in the East Asian population. Of note, this variant is reported as a benign germline variant in ClinVar (https://www.ncbi.nlm.nih.gov/clinvar/variation/41632/). Clinical correlation is recommended.