The deformation of the carpal bones and the rod-shaped changes of the metacarpals are seen in mucopolysaccharide storage disease type VI, also known as Maroteaux-Lamy syndrome and polytrophic dwarfism. It is an autosomal recessive disorder. What are the causes of carpal hypoplasia and rod-shaped changes in the metacarpals? The following is a brief introduction; the disease is autosomal recessive. The basic biochemical defect of the disease is the reduced activity of N-acetylgalactosamine-4-sulfatase, which hydrolyzes the sulfate in N-acetylgalactosamine-sulfate vinegar, a reaction that occurs in both chondroitin-4-sulfate and dermatan sulfate. This gene is localized at 5q12 to q13 and may have 2 alleles. In this type of human, chondroitin-4-sulfate and dermatan sulfate can be deposited in various tissues and cause disease because of insufficient activity of this enzyme.