Epidemiological findings looking at the melatonin pathway genes have associated some loci in MTNR1A with a decreased breast cancer risk, however, all the loci in AANAT that encode enzymes involved in melatonin synthesis and in the control of day/night rhythm of melatonin production, did not demonstrate any association with breast cancer risk16. The gene discussed is MTNR1A; the disease is breast carcinoma.