Interacting Gene/EnzymeAllele nameGenotype(s)Defining Change(s)Type(s)DescriptionDetailsMultidrug resistance protein 1---(T;T) / (C;T)T AlleleEffect Directly StudiedPatients with this genotype may have an increased analgesic response to morphine.DetailsMu-type opioid receptor---(A;A)A AlleleEffect Directly StudiedPatients with this genotype may have an increased analgesic response to morphine.Details