SNP rs4073 is a functional variant, with the AA genotype reported to be associated with increased IL8 production (Hull et al., 2000).
After Reyes-Gibby et al., 2007, a subsequent study of pain and analgesic response in lung cancer by the same group (Reyes-Gibby et al., 2008) revealed no association of rs4073 with pain severity. There was a trend (not statistically significant) for higher morphine equivalent daily dose.