Mandy Sellars (born 20 February 1975 in Lancashire, United Kingdom) is a woman with a rare genetic mutation that has resulted in extraordinary growth in both of her legs. In 2006, some doctors diagnosed Sellars as having Proteus syndrome, a very rare condition thought to afflict only 120 people worldwide, but more recent diagnoses have focused on a PIK3CA gene mutation. Some reports still describe her affliction as a rare form of Proteus Syndrome, but Sellars herself has disputed the diagnosis.