CLCN7 and osteosclerosis: The OPT was identified to be due to a CLC‐7 mutation, Gly215Arg, and thus, this family has Albers–Schonberg disease, which is characterized by diffuse, symmetrical osteosclerosis mainly affecting the spine, pelvis and skull, increased fracture rate, and severe vision loss beginning in childhood in ∼20% of patients [Waguespack et al., 2007; Bollerslev et al., 2013].