Choline is a direct precursor of acetylcholine, which is one of the neurotransmitters in the central and peripheral nervous system. SLC5A7, also known as choline transporter (CHT1), is a Na+- and Cl-- dependent high-affinity transporter that mediates choline uptake for acetylcholine biosynthesis in cholinergic neurons. Polymorphic variation in the SLC5A7 gene is suggested to be associated with heart-rate variability.