Genetic variant of the human homologous recombination-associated gene RMI1 (S455N) impacts the risk of AML/MDS and malignant melanoma.

The newly identified protein BLAP75/RMI1 associates with the helicase BLM and is critical for the function of the homologous recombination complex. Mutations altering BLM function are associated with highly elevated cancer susceptibility (Bloom's syndrome). We have analyzed the common polymorphism Ser455Asn in RMI1 and its association with cancer risk in acute myeloid leukemia (AML, N=93), myelodysplatic syndromes (MDS, N=74), and malignant melanoma (MM, N=166). Two control groups were used: one population-based (N=119) and one recruited from spouses of cancer patients (N=189). The results showed a consistent pattern, where carriers of the Asn variant had a significantly increased risk of AML/MDS. The risk of AML/MDS for SerAsn+AsnAsn subjects was odds ratio (OR)=1.7, 95% confidence interval (CI) 1.1-2.5 or MM was OR=1.5, 95% CI 1.0-2.2. Age might modify the effect of RMI1 on cancer risk. This was most evident for MM: AsnAsn homozygotes > or =64 years showed OR=2.7, 95% CI 1.1-6.0, whereas individuals <64 years showed OR=0.87, 95% CI 0.31-2.5. These results indicate a role of low-penetrance genes involved in BLM-associated homologous recombination for cancer risk.