Reflecting this principle, the Human Genetics Society of Australasia (HGSA) Newborn Screening committee has excluded ornithine transcarbamylase (OTC) deficiency and non-ketotic hyperglycinemia (NKH) from their screening panel, primarily based on two key observations: the early onset of symptoms relative to the neonatal screening result and the lack of reliable laboratory markers. This evidence concerns the gene OTC and propionic acidemia.