Abstract
Marble brain disease, also known as Guibaud-Vainsel syndrome, is a syndrome consisting primarily of renal tubular acidosis, cerebral calcification and osteopetrosis. The majority of reports originate from the Middle East. It is an autosomal recessive condition owing to carbonic anhydrase type II deficiency in renal and brain cells with a variant form of osteopetrosis. We report two siblings with this condition from Saudi Arabia. Both cases improved in both somatic growth and mental development after commencing treatment for renal tubular acidosis in the form of alkaline therapy and potassium supplementation.