Genome study suggests a fifth of adults carry disease mutations

Approximately 22 percent of healthy adults carry mutations that are associated with disease, found the first ever randomised clinical trial using whole-genome sequencing.

However, in most cases, individuals showing these 'disease-causing' DNA changes were asymptomatic for the suspected condition.

ʹSequencing healthy individuals will inevitably reveal new findings for that individual, only some of which will have actual health implications,ʹ said lead author Dr Jason Vassy, a primary care clinician-investigator at Veteran Affairs Boston Healthcare System.

In the study published in the Annals of Internal Medicine, 100 subjects were randomised so that half underwent whole-genome sequencing. The remaining 50 reported only their family medical history to a physician.

The sequencing technique examined five million single nucleotide polymorphisms (SNPs) across 4631 genes. While 11 showed changes in at least one DNA base associated with a rare disease, only two individuals exhibited symptoms of the suspected disease.

The work suggests that carrying a genetic risk marker does not necessarily mean that an individual has, or will develop, a certain disease. However, there are concerns that the knowledge that a person is carrying such a marker could result in unnecessary emotional stress and increased medical costs.

Dr Barbara Koenig, a medical anthropologist and director of the University of California San Francisco Bioethics Program who was not involved in the work, told Science: ʹIt is just hard to know how all this information is going to be brought together in our pretty dysfunctional healthcare system.'

However, Dr Christa Martin, a geneticist at Geisinger Health Systems, Pennsylvania, who was not involved in the work, provided a more positive outlook, and suggested that providing individuals with more information about their health is beneficial. She told Science: ʹMany of [the] patients [in the study] are making health behavioural changes, so they are using the information in a positive way.'

The implications of whole-genome sequencing for health are not yet fully understood. Further work in larger and more diverse cohorts will be needed to establish whether genome sequencing is beneficial or detrimental for healthy individuals.