Ontlametse Phalatse, a sufferer of the rare genetic disorder Progeria, which causes premature ageing, has died.
Expected by doctors to only live until the age of 14, Phalatse last month celebrated her 18th birthday.
She was the only known black female born with this disease.
According to an update on her Facebook page, Phalatse experienced breathing difficulties on Tuesday and was rushed to Hebron Clinic before being referred to Dr George Mukhari Academic Hospital in Pretoria.
"The doctors did everything possible to save her but unfortunately she passed on. She was surrounded by her mother, brother, family members and friends.
"The Phalatse family and Ontlametse Phalatse Trust would like to thank the nurses at Hebron Clinic and the Staff at Dr George Mukhari [Hospital] for their compassion and their effort in trying to save her.
"Our hearts are filled with pain and sadness but Ontlametse as we know her would want us to carry on with her courageous spirit. We will miss you sorely, Tsontso, our first lady. May you find eternal peace among the angels."
She celebrated her birthday on March 25, and two days before that fulfilled her dream of meeting President Jacob Zuma before she turned 18.
Zuma surprised Phalatse with a basket filled with flowers and a cake at his Mahlamba Ndlopfu Presidential House in Pretoria.
The president described her as "very sharp" and articulate.