TAC1 and hyperinsulinemic hypoglycemia, familial, 4: In the second step, the inclusion of substance P (β = 4.33) enhanced the relationship between BPRS deficiency energy factor score and oxytocin level (β = −0.65) based on the magnitude of the standardized beta-coefficient in Step 2 (F = 5.36, p < 0.01; ΔR2 = 0.023).