Deficiency or lack of HGPRT leads to increased concentration of uric acid, triggering several diseases such as nephrothiasis (kidney stones), hyperuricemia (high levels of uric acid in the blood), gout, kidney dysfunction, uricosuria (uric acid in the urine), crystal formation in the joints, motor and neurological dysfunction such as occasional choreoathetosis (involuntary movements) or spasticity, dysarthria (los of the ability to articulate words normally) and dysphagia (difficulty swallowing food or liquids) as well as self-mutilation of the lips, tongue and fingers4-6. Here, HPRT1 is linked to nephrolithiasis.