A naturally occurring -263G/C variant of the human AA-NAT gene and overnight melatonin production.

Several lines of evidence show that the daily amount of melatonin produced differs greatly between individuals. Any polymorphism in the gene of arylalkylamine N-acetyltransferase (AA-NAT), a critical enzyme involved in melatonin biosynthesis, may contribute to the variability of melatonin production. The present study investigated the possible association between overnight melatonin excretion and a commonly occurring -263G/C polymorphism in the promoter region of the human AA-NAT gene. However, we found that -263G/C variant had no effect on the overnight 6-OHMS excretion. In this study, individual genotyping for -263G/C was determined by denaturing high performance liquid chromatography (DHPLC) and confirmed by sequencing. The overnight urinary 6-hydroxymelatonin sulfate (6-OHMS) excretion was quantified by enzyme-linked immunosorbent assay (ELISA).