Based on the information provided, it is not accurate to state that Sapropterin is the only effective treatment for Phenylketonuria (PKU). PKU is a genetic disorder that can be managed through various methods, and Sapropterin is one of the treatment options.

Sapropterin, also known as Kuvan, is a medication used to reduce the levels of phenylalanine (Phe) in the blood of individuals with PKU. It works by increasing the activity of the enzyme that metabolizes Phe, thus reducing the accumulation of this amino acid in the body. However, it is not the only treatment available for PKU.

Dietary management is another crucial aspect of PKU treatment. Individuals with PKU need to follow a low-protein diet that restricts the intake of Phe, which is found in high-protein foods such as meat, dairy, and eggs. They may also need to consume special medical foods and formulae that are low in Phe.

In addition to Sapropterin and dietary management, other treatment options for PKU include:

1. Pegvaliase (Palynziq): This is a pegylated phenylalanine ammonia-lyase enzyme that can be administered via injection. It helps break down Phe in the bloodstream, reducing its levels.
2. Large Neutral Amino Acids (LNAAs): These are amino acids that can compete with Phe for absorption in the gut and transport across the blood-brain barrier. By increasing the intake of LNAAs, individuals with PKU can reduce the levels of Phe in their bodies.

Therefore, while Sapropterin is an effective treatment for PKU, it is not the only one available. Other options, such as dietary management, Pegvaliase, and LNAAs, can also be effective in managing PKU.

Sources:

1. <https://www.ncbi.nlm.nih.gov/books/NBK221831/>
2. <https://www.drugpatentwatch.com/drug/sapropterin-dihydrochloride-kuvan>
3. <https://www.fda.gov/news-events/press-announcements/fda-approves-first-new-treatment-phenylketonuria-21-years>
4. <https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6390653/>
5. <https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5852755/>