PRL and hyperprolactinemia: Osmanova et al. (2019) found an association between two variants in the DAT (SLC6A3) gene and hyperprolactinemia in the subgroup of patients taking risperidone/paliperidone in 446 Caucasian schizophrenia patients. Smith et al. (2004) reported that the short allele of the 5-HTTLPR indel polymorphism was associated with less of an increase in prolactin and cortisol than the long/long genotype in control participants. Lee et al. (2007) found a nominally significant association between PRL and PRLR tagSNPs and plasma prolactin levels in 95 advanced breast cancer cases.