Our study seeks to investigate the potential small molecule inhibition of the kinase that regulates BCKDC by applying a novel activity of sodium phenylbutyrate (NaPBA), in MSUD. Sodium phenylbutyrate is has been used to treat patients with urea cycle disorders (UCDs). In our extensive studies with UCDs, we noted that patients on therapy with NaPBA had decreased plasma levels of BCAA. This led us to hypothesize that NaPBA has effects on BCAA metabolism.