After analyzing the available information, the genetic finding that suggested sapropterin as a potential solution is related to Phenylketonuria (PKU), a genetic disorder caused by a mutation in the PAH gene [3]. PKU results in an accumulation of phenylalanine (Phe) in the brain, which can lead to intellectual disability, seizures, and other neurological problems [3].

In the article "Pharmacological treatment of phenylketonuria: past, present, and future" [2], it is mentioned that the discovery of the PAH gene mutation and the understanding of the biochemical pathway of Phe metabolism led to the development of sapropterin as a potential treatment for PKU. Sapropterin, also known as tetrahydrobiopterin (BH4), is a cofactor that plays a crucial role in the metabolism of Phe [1][2].

The drug patent watch page for sapropterin [1] further supports this finding, as it states that sapropterin is used for the treatment of PKU and works by increasing the activity of the PAH enzyme, thereby reducing the levels of Phe in the brain.

Therefore, the genetic finding that suggested sapropterin as a potential solution for PKU is the mutation in the PAH gene, which leads to a deficiency in the PAH enzyme and an accumulation of Phe in the brain. Sapropterin works by increasing the activity of the PAH enzyme, thereby reducing the levels of Phe in the brain.

Sources:

* [1] <https://www.drugpatentwatch.com/p/tradename/SAPROPTERIN>
* [2] <https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10641558/>
* [3] <https://www.nhs.uk/conditions/phenylketonuria/>