Like CatD‐deficient mice [370], CatB‐ and CatL‐deficient mice also display pronounced lysosomal storage diseases that lead to extensive neuronal death in the CNS and to the development of pronounced brain atrophy due to massive apoptosis of neurons in the cerebral cortex and cerebellar Purkinje and granule cell layers. The gene discussed is TYRP1; the disease is lysosomal storage disease.