Mice of the B6.Cg-Tg (Prnp-SNCA*A53T)23Mkle/J strain (further mut(PD)), a genetic model of PD, and control wild-type (WT) mice that had been born and reared under SPF conditions also endured the GPC-supplemented diet well. The gene discussed is PRNP; the disease is Parkinson disease.