Parkinson's disease (PD) Harrison died on June 25 "surrounded by those he loved" following a lengthy struggle with Parkinson's disease, according to his son Rick in an Instagram message. He was 77 years old. "He will be greatly missed by our family, the crew at Gold & Silver Pawn, and his many followers all around the world," Rick said on Instagram. Rick also wrote that his father had multiple myeloma, a cancer of plasma cells that produces large amounts of monoclonal protein in the blood. The myeloma attacked Harrison's bones, causing pain and disability. He was diagnosed with the disease in 2016. Multiple myeloma is the second most common type of cancer of the blood. It affects about 14,000 people in the United States and causes approximately 10,000 deaths per year. Myeloma can develop at any age but is more common in older adults; it occurs without known causes. The first sign of multiple myeloma may be short periods of severe bone pain without apparent cause. Other signs include fatigue, weakness, sore throat, fever, changes in the color of urine or stools, depression, loss of appetite, weight loss, trouble sleeping, and heart failure. A routine check-up can identify multiple myeloma early, when treatments are most effective. There is no cure for multiple myeloma. Treatment aims to reduce the amount of abnormal proteins in the blood, control symptoms, and prolong life.