While neurodegeneration in substantia nigra has not been described in CLN6 disease (either humans or sheep), changes in dopamine have been found in Batten disease caused by mutations in the CLN2 gene in humans [32] and in a mouse model with a mutation in Cln3 [33] as well as in other neuronal ceroid lipofuscinoses [34,35]. The gene discussed is TPP1; the disease is juvenile neuronal ceroid lipofuscinosis.