rs9561778 is a SNP in the ATP-binding cassette, sub-family C (CFTR/MRP), member 4 ABCC4 gene.
A stepwise case-control study of ~400 breast cancer Japanese patients receiving cyclophosphamide-based combination chemotherapy, roughly divided equally between those having or not having serious adverse drug reactions (ADRs), concluded that carriers of rs9561778(T) allele had a ~2x higher risk of ADRs. The ADRs for these patients tended to be gastrointestinal toxicity and leukopenia/neutropenia.[PMID 19696793]
|qualified_impact||Insufficiently evaluated pharmacogenetic|