PSPH and Williams syndrome: PSPH is located in chromosome 7p11.2, which encodes enzymes, and was originally known as a mediator involved in the third and last step in L‐serine formation.7 Previous studies have reported that PSPH mainly participates in multiple fundamental aspects of cell behavior by providing amino acid, neurotransmitters, and nucleotide substrates necessary for cell proliferation and division.8, 9 Additionally, PSPH participates in neuronal signal transduction and methylation.10 Thus, deficiency of this protein is thought to be linked to Williams syndrome and neural tube defects.