Presence of a second, clearly pathogenic variant in the same MMR gene and especially if observed in trans, is another feature that may help in classification of a VUS, since the phenotype of carrying one mutant allele (Lynch syndrome) is very different from the phenotype of bi‐allelic mutation carriers (Constitutional Mismatch Repair Deficiency – CMRD – Syndrome 51, 52. The gene discussed is MRC1; the disease is chylomicron retention disease.