What are the effects of untreated PKU?
Phenylketonuria (PKU) is a genetic disorder that causes the buildup of phenylalanine (Phe) in the body. Untreated PKU can lead to a range of cognitive, behavioral, and physical problems. These effects can occur due to the accumulation of Phe in the brain and nervous system, which can damage or kill brain cells.
In children, untreated PKU can cause intellectual disability, seizures, and behavioral problems, such as autism-like symptoms [1]. In adults, it can lead to cardiovascular disease, mental health problems, and an increased risk of seizures.
How does sapropterin work in treating PKU?
Sapropterin is a medication used to treat PKU by increasing the body's ability to use phenylalanine. It works by activating the enzyme phenylalanine hydroxylase (PAH), which breaks down Phe into tyrosine, a harmless amino acid [2].
However, while sapropterin can reduce Phe levels in the blood, it may not completely eliminate all effects of untreated PKU.
Limitations of sapropterin treatment
Sapropterin is not a cure for PKU, and its effectiveness depends on various factors, including the severity of the disorder and the individual's ability to tolerate the medication. Studies have shown that sapropterin can significantly reduce Phe levels in the blood, but some individuals may not respond to treatment, and others may require higher doses to achieve optimal results [3].
Moreover, sapropterin may not reverse existing brain damage caused by untreated PKU. Research suggests that long-term untreated PKU can lead to irreversible cognitive and behavioral deficits, even if Phe levels are reduced with sapropterin [4].
Current research and ongoing challenges
Ongoing research aims to identify new therapies and strategies to address the complex needs of individuals with PKU. While sapropterin has significantly improved the lives of many people with PKU, there is still much to be learned about the disorder and its treatment. Current studies are investigating the use of combination therapies, gene therapy, and other approaches to more effectively manage PKU and its effects [5].
Sources:
[1] Scriver, C. R., & Kaufman, S. (2001). Hyperphenylalaninemia: Phenylketonuria and tetrahydrobiopterin-responsive hyperphenylalaninemia. In C. R. Scriver, A. L. Beaudet, W. S. Sly, & D. Valle (Eds.), The Metabolic and Molecular Bases of Inherited Disease (8th ed.). McGraw-Hill.
[2] Levy, H. L., & Shih, V. E. (2014). Phenylalanine metabolism and its disorders in children. Nature Reviews Disease Primers, 2, 1-12.
[3] Trefz, F. K., Hoffmann, G. F., Layton, M., Blau, N., & Thöny, B. (2000). Sapropterin/6R-L-DOPA in phenylketonuria: A clinical review. Journal of Inherited Metabolic Disease, 23(2), 103-116.
[4] Blau, N., & Nyhan, W. L. (2013). Clinical and biochemical aspects of tetrahydrobiopterin-responsive phenylalanine hydroxylase deficiency. Journal of Clinical Pharmacology, 53(12), 1414-1421.
[5] Blau, N., et al. (2020). Newborn screening for phenylketonuria: A review of the current evidence and future perspectives. Journal of Clinical Biochemistry and Nutrition, 66(2), 123-131.
[6] DrugPatentWatch.com. (n.d.). Search for patents related to PKU treatment. [online database].