Adult polyglucosan body disease body disease do not have identified mutations in the "GBE1" gene. In these individuals, the cause of the disease is unknown. Along with evaluation of the symptoms and a neurological examination, a diagnosis can be made based on genetic testing. Whether or not a person is making sufficient amounts of functional glycogen branching enzyme can be determined by taking a skin biopsy and testing for activity of the enzyme. Examination of tissue biopsied from the sural nerve under a microscope can reveal the presence of polyglucosan bodies. There will also be white matter changes visible in a magnetic resonance imaging
John Ritter known as a coloboma in his right eye. His father, Tex Ritter, was a singing cowboy/matinee star, and his mother, Dorothy Fay (née Southworth), was an actress. He had an older brother, Thomas Matthews "Tom" (born January 8, 1947). Ritter attended Hollywood High School, where he was student body president. He attended the University of Southern California and majored in psychology with plans to have a career in politics. He later changed his major to theater arts and attended the USC School of Dramatic Arts (formerly School of Theatre). Ritter was a member of Phi Gamma Delta fraternity at USC.