CHAT and Miosis: In connection, in Genome-wide association studies (GWASs)—studies that compare the genotype of a disease to a normal control, identifying a statistically significant array of small differences, most often single-nucleotide polymorphisms, which correlate with a trait of interest which is not usually caused by a monogenic mutation [29]—the CHAT gene (encoding the enzyme choline O-acetyltransferase), a gene which modulates the pupillary response of miosis, has also been associated with PACG [16].