David Vetter lived his whole life sealed off from the outside world in a completely sterile environment. He was born with a rare genetic disorder, Severe Combined Immunodeficiency Disease, which made him hugely susceptible to infections. He died from the disease at the age of 12 on 24 February 1984, when a bone marrow transplant failed. Rachael Gillman has been speaking to his mother Carol-Ann Demaret.(Photo: David Vetter and his mother Carol-Ann Demaret Credit: Carol-Ann Demaret)