CLCN7 and osteopetrosis: In particular, osteopetrosis, a disease characterized by dense and brittle bones, is the most common disease associated with CLC-7 mutation, with more than 50 distinct pathogenic mutations identified to date (Chalhoub et al., 2003; Cleiren et al., 2001; Kasper et al., 2005; Kornak et al., 2001; Lange et al., 2006; Sartelet et al., 2014; Schulz et al., 2010; Weinert et al., 2010).