Professor Edwin Kirk, medical director of the education and screening programme at Sydney schools, attributes its success to community ownership.

"They don't just fund it. They have very real input into decisions about how the programme is run.

"There has been considerable community support for screening over many years now and the participation rate at the schools is close to 100 per cent as a result. I would also say that we know that it works - which means it is possible to spare families the pain of losing a child to Tay-Sachs disease or one of the other conditions we screen for. That's a wonderful thing and I'm really glad to have the opportunity to be part of it."

For the first half of the year, team members go out to eastern Sydney, where the largest number of Ashkenazim live, reaching pupils in Jewish schools or schools with a high Jewish student population.

"Students in their second last year of school are given an education session, with the opportunity to ask questions," Prof Kirk explained. "Those who wish to have testing [the great majority] then have a saliva sample collected, which we screen for variants in nine disorders.

"The results are returned later in the year, with involvement of genetic counsellors for those who are found to be carriers.

"In addition to this, members of the community can be tested at any time during the year but they do pay a fee.

"The longest running component is Tay-Sachs screening and in the 20 years since it started, no affected child has been born to a couple who have been screened. We would have expected several affected children based on the frequency of the condition."