Phenylketonuria (PKU)

Phenylketonuria (PKU) is a disorder that can be passed down from generation to generation. It is caused by a deficient hepatic phenylalanine hydroxylase (PAH), which is an enzyme in the liver that catalyzes the conversion of phenylalanine to tyrosine, using the coenzyme, tetrahydrobiopterin (BH4). One treatment for PKU would be to have a restricted diet because PKU does not allow for the process of phenylalanine, which is a protein found in many foods (Scala et al 2015). With the help of BH4, patients are able to decrease their blood Phe concentration and/or increase their dietary tolerance. If PKU were to go untreated, it could result in neurological deformities such as brain damage. There are many other symptoms other than brain damage that patients with PKU experience. Patients may also have weaker bones, a smaller head, psychiatric disorders, and more. They also tend to have fairer skin and lighter eyes as a result from phenylalanine not being able to transform into melanin. Not only is there …show more content…
In a study conducted by Anjema et al, the researchers used the 48 hour BH4 loading test to help predict BH4 responsiveness. In it, they found that less than half of their patients were BH4 responsive. Some patients were able to respond to BH4 within 24 hours and others at 48 hours. After the 48 hours were over, an extension phase was followed and it showed that those with true-positive BH4 responsiveness were able to increase intake of natural proteins. Those who responded late during the 48 hours BH4 loading test and were true responders to BH4 showed no difference in natural protein intake when compared to those who had responded in 24 hours. Genotypes were also a factor that showed BH4 responsiveness in this research. Those that had at least one genotype with at least one mutation known to be linked to long-term BH4 responsiveness showed a high rate of true response (Anjema et al