The treatment paradigm for HCRC is progressively shifting towards individualized strategies, with microsatellite instability (MSI) and dMMR assays based on molecular tumor subtype classification to aid in the diagnosis of LS and to identify patients eligible for immune checkpoint inhibitor therapy, somatic biomarkers, such as KRAS and BRAF V600E, are primarily used to distinguish between sporadic and MSI-H HCRC and can guide targeted therapy [19,20]. The gene discussed is BRAF; the disease is Leigh syndrome.