An obvious way to dissuade people from resorting to postal tests is to give them fast, efficient access to NHS services.

An unpublished survey carried out by the Genetics Interest Group showed waiting times for genetics consultations ranging from a few weeks in some areas to over a year in others, with an average of two to three months.

But the rapidly increasing demand for cancer genetics is threatening to swamp services.

A primary care questionnaire aimed at filtering demands for cancer tests, piloted in the West Midlands, has given promising results. GPs give the form to worried patients who ask about cancer tests.

Their written answers to questions about cancer deaths in the family are assessed at genetics centres so that clinic appointments can be reserved for those at highest risk.

Such approaches can help deal with the current rush for genetic tests, but as the human genetic map is completed in the early years of the next century they will be hard-pressed to contain future demand.