PRPSAP2 is a regulatory protein that negatively modulates phosphoribosyl pyrophosphate (PRPP) synthetase activity, a key enzyme in purine and pyrimidine nucleotide biosynthesis 1. As an enzyme inhibitor, PRPSAP2 functions to regulate the pentose phosphate pathway, which is critical for nucleotide synthesis and cellular proliferation 1. The protein localizes to the cytoplasm and exhibits enzyme regulator activity through protein-protein interactions [GO annotations]. PRPSAP2 has emerging relevance in neurological and oncological diseases. Genomic analysis identified PRPSAP2 as a susceptibility gene associated with genetic generalized epilepsy (GGE) through immune-related pathways 2, and it was selected as a predictive feature for inattention symptom changes in ADHD, suggesting involvement in neurodevelopmental processes 3. In osteosarcoma, PRPSAP2 is located within the frequently amplified chromosome 17 17p11.2-p12 (amplified in ~25% of cases), where it is among nine candidate oncogenes showing significant correlation between copy number and expression levels 4. While PRPSAP2 was not functionally validated for oncogenic properties in direct overexpression studies 5, its inclusion among significantly amplified genes suggests potential contribution to tumor progression through enhanced PRPP pathway activity.