As the cost of DNA testing falls, publicly-funded population DNA screening is becoming realistic. Population DNA testing through the health-care system would ensure higher standards of quality control. It would also facilitate equity-of-access to testing that is required to maximise population health benefits. If widespread testing is not provided by a public health-care system, consumers will likely turn to cheap internet-based alternatives.
DNA testing estimates risk well for certain types of diseases, mostly those caused by single gene changes. These are distinct from other common diseases where genetic risk accumulates from hundreds of genes and is harder to predict. Potential candidates for screening include cancers such as breast and ovarian cancer caused by the BRCA genes, colorectal and other cancers caused by Lynch syndrome, inherited high cholesterol and other types of genetic heart disease.
Couples who intend to have children can undergo genetic tests to check whether the combination of their genes will predispose their offspring to a genetic disorder. If yes, then the couple may decide not to have children or to receive genetic counselling. Genetic diseases for which one can screen include Tay-Sachs, cystic fibrosis and Gaucher's disease.
Despite its potential to save lives and money, DNA screening raises ethical questions. Some people may not want testing due to concerns including DNA privacy, insurance discrimination or the “right not to know”. The shared nature of DNA also means testing implicates family members, and issues such as non-paternity may arise.
In 1999 it was reported that genetic testing on embryos was forbidden in France and Germany on ethical grounds—for fear that it could be used to produce the perfect child—but was legal in Belgium, Britain and the Netherlands.
Young adults are most likely to benefit from screening, being old enough to provide informed consent, but below the average age of onset for preventable adult genetic conditions, and below the average age of having their first child.