Milton Wexler, who has died aged 98, set out to find a cure for Huntington's disease after his ex-wife was diagnosed with the disorder.
Huntington's disease is an inherited genetic disorder which causes the premature death of nerve cells in the brain, triggering mental and physical deterioration.
In 1972 Wexler heard about a village in Venezuela that had been riddled with Huntington's for generations. Eventually researchers traced the disease back to one woman whose descendants numbered some 9000 people.
In 1983 a molecular geneticist, working on blood samples sent from the village, located human chromosomes that contained the Huntington's disease gene. A decade later the gene itself was identified.
The discovery demonstrated that it might be possible to map the entire human genome - a task that was completed in 2003.
