OSTM1 and osteopetrosis: At least in mice, dysfunction of ClC-7/Ostm1 additionally leads to a neuronal ceroid lipofuscinosis (NCL)-like lysosomal pathology (Kasper et al., 2005; Lange et al., 2006), and a severe form of osteopetrosis is accompanied by neurodegeneration and accumulation of ceroid lipofuscin in humans (Steward, 2003).