In the present study, the expression levels of the PHGDH, PSAT, and PSP genes were significantly lower in pancreatitis-associated-DHAV-1-infected ducklings than in the classical-type DHAV-1 group, suggesting that serine metabolism disorders are involved in the pancreatitis-associated DHAV-1 infection. The gene discussed is PSAT1; the disease is pancreatitis.