DPYD and hyperinsulinemic hypoglycemia, familial, 4: One hundred sixty-six (166) (4.5%) patients were carriers of one defective DPYD variant (Table 2), and these patients were predicted to have intermediate metabolism according to the activity score of DPYD alleles (1 or 1.5) (see the “Methods”).6 The presence of a mutation in the DPYD gene has a low positive predictive value (PPV) to identify individuals with partial DPD deficiency (Table 3), but the PPV of a DPYD mutation is higher when [UH2]:[U] is used to evaluate DPD activity rather than [U] (PPV 33% vs. 16%, respectively).