Osteopetrosis with renal tubular acidosis is a rare disorder characterized by osteopetrosis (see this term), renal tubular acidosis (RTA), and neurological disorders related to cerebral calcifications. The disease is Orphanet rare-disease nomenclature entry Orphanet_2785 (Osteopetrosis with renal tubular acidosis). Also known as: Carbonic anhydrase 2 deficiency, Guibaud-Vainsel syndrome, Marble brain disease, Mixed RTA, Mixed renal tubular acidosis, Renal tubular acidosis type 3.