Rs28936679

rs28936679, also known as Ala129Thr or A129T (and also G619A), is a SNP in the aralkylamine N-acetyltransferase AANAT gene. The AANAT protein plays a unique role in vertebrate biology by controlling rhythmic production of melatonin in the pineal gland. Its activity increases 10- to 100-fold at night, leading to increased production and release of melatonin.

In a 2003 report about Japanese patients with a sleep disorder known as susceptibility to delayed sleep phase syndrome, patient genotypes had a higher frequency of the rs28936679(A) allele.

A later report based on Brazilian (primarily Caucasian) patients including those with delayed sleep phase syndrome found no variation at this SNP.