What is Phenylketonuria?
{{Infobox disease | Name = Phenylketonuria | Image = | Caption = [[Phenylalanine]] | DiseasesDB = 9987 | ICD10 = {{ICD10|E|70|0|e|70}} | ICD9 = {{ICD9|270.1}} | ICDO = | OMIM = 261600 | OMIM_mult = {{OMIM2|261630}} | MedlinePlus = 001166 | eMedicineSubj = ped | eMedicineTopic = 1787 | eMedicine_mult = {{eMedicine2|derm|712}} | MeshID = D010661 }} '''Phenylketonuria''' ('''PKU''') is a [[Genetics|genetic disorder]] (a disease a person is born with) where a person's body cannot break down an [[amino acid]] called '''phenylalanine'''. Amino acids are necessary to make [[proteins]], an important part of the human body. Phenylalanine only comes from the food we eat; our bodies do not make any by themselves. == How it works == Average people produce an [[enzyme]] called '''phenylalanine hydroxylase'''<ref>{{Cite web|title=PAH gene: MedlinePlus Genetics|url=https://medlineplus.gov/genetics/gene/pah/|access-date=2025-01-08|website=medlineplus.gov|language=en}}</ref> in their bodies. When they ingest phenylalanine, the body cannot use it, so this enzyme changes phenylalanine into '''tyrosine''',<ref>{{Cite journal|last=Matthews|first=Dwight E.|date=2007-06|title=An Overview of Phenylalanine and Tyrosine Kinetics in Humans|url=https://pmc.ncbi.nlm.nih.gov/articles/PMC2268015/|journal=The Journal of Nutrition|language=en|volume=137|issue=6|pages=1549S–1555S|doi=10.1093/jn/137.6.1549S|issn=0022-3166}}</ref> which the body can use. In people with PKU, very little or no enzyme is made. Since the phenylalanine they eat is not being changed into tyrosine, it builds up in their bodies. This can cause problems with the way their bodies work. == Symptoms == [[Symptom]]s vary from person to person. Because of the rarity of PKU, many symptoms go [[diagnosis|undiagnosed]] or unrecognized. In addition, there are variations in the categories of PKU individuals. There are untreated, early treated, late treated, those returning to diet, Hyperp