Tarui disease (also known as phosphofructokinase deficiency, or glycogen storage disease type VII) was first described in 1965 by the Japanese physician Seiichiro Tarui and his co-workers. It is caused by deficient activity of the enzyme phosphofructokinase (muscle PFK or PFKM) in muscle tissue. Lack of this enzyme means that a complex sugar called glycogen is unable to be broken down. For more information about Tarui Disease click here.