Transgenic mice expressing a human mutant alpha-galactosidase with an R301Q 
substitution, which was found in a patient with a variant form of Fabry disease, 
were established. The mice transcribed a sufficient amount of 
alpha-galactosidase mRNA, but the steady-state levels of the enzyme protein were 
decreased in liver, kidney and heart, only residual activity being detected in 
these tissues. The mice will be useful for the clarification of the defective 
regulation of the structurally altered enzyme protein expressed by the mutant 
gene at the organ or individual level as well as for the evaluation of drugs 
that stabilize and/or activate the mutant alpha-galactosidase.