Ontlametse Phalatse
One of two black South Africans born with the rare genetic disorder progeria, Ontlametse Phalatse died on 11 April 2017Twitter

South Africans have been paying tribute to Ontlametse Phalatse, an 18-year-old girl living with progeria, a rare genetic disorder that causes rapid ageing, described as the "champion of positivity", who has died.

Phalatse, one of two black South African girls living with the disorder, died on 11 April at Dr George Mukhari Academic Hospital in Ga-Rankuwa' outside Pretoria. She outlived doctors' predictions by four years.

Regarded as an inspiring figure, Phalatse celebrated her birthday with President Jacob Zuma in March.

South Africans took to Twitter to pay tribute to the young woman using the hashtags #OntlametsePhalatse and #RIPOntlametse, which were trending.

Using a picture of Phalatse and Zuma's meeting, the government expressed its condolences.

Daily Monitor journalist Stephen Kafeero also paid tribute to the young woman, describing her as "a candle that defied darkness with hope".

Karyn Maughan‏, a journalist working for eNCA channel, cited a January 2017 quote by Phalatse, which said: "I will devote myself to making children courageous."

User Karabo Mokonyane, from Johannesburg, wrote: "You fought a good fight, You finished the race, You have kept the faith, Rest now you gentle one".

Hutchinson-Gilford progeria syndrome is an extremely rare genetic disorder in which the symptoms resemble aspects of ageing at a very early age. The condition affects one in 8 million live births and those born with it typically live to between their mid-teens and early twenties.

The condition occurs as a new mutation and is rarely inherited as carriers usually do not live to reproduce. Symptoms and signs include wrinkled skin, atherosclerosis, kidney failure, loss of eyesight, a tightening and hardening of the skin on the trunk of the body, and brittle and fragile bones.