We synthesized the novel fused pyridine derivative T-3833261 based on structure-based drug design using the X-ray crystal structure of PRS protein bearing our lead molecule (Fig 1A and 1C) and found that this compound showed comparable PRS enzymatic inhibition (PRS IC50: 3.6 nM) to HF (PRS IC50: 8.7 nM) in an ATP/PPi exchange assay utilizing PRS (Fig 1D). This evidence concerns the gene WNK3 and hydrops fetalis.