Some studies show that the variant T allele was associated with several loss-of-function phenotypes reducing nNOS activity, namely infantile hypertrophic pyloric stenosis [48], cerebral malaria [49], cutaneous melanoma [50], reduced markers of central serotonergic activity [51] and schizophrenia [30,52,53]. This evidence concerns the gene NOS1 and hypertrophic pyloric stenosis.