Imagine looking at your DNA and finding that you rank among the 10% of people with the highest genetic risk for diabetes, heart disease or another common condition. You feel healthy, have no symptoms and may never develop the disease. Yet, your genetic profile could place you in a group considered more susceptible to it.That is the intriguing picture emerging from a new study led by researchers at the UK’s University of Exeter. The team found that the average person may fall among the 10% at highest genetic risk for nearly three common conditions out of 28 examined, including diabetes, cardiovascular disease and schizophrenia.
The surprising amount of variation in human DNA
Every person’s genome contains approximately five million genetic variants, or DNA locations that differ between individuals, according to the study published in the journal Genome Medicine.Many of these differences have little or no known effect on health. Others can influence traits and biological processes, from lactose intolerance to how a person responds to medication.Researchers also found that each person carries between one and three rare genetic variants previously associated with serious inherited diseases. In addition, individuals carry around 50 rare variants whose clinical significance remains uncertain.
What does a high genetic risk actually mean?
To understand how common genetic susceptibility can be, the researchers examined polygenic risk scores. These scores combine information from multiple genetic variants to estimate a person’s relative genetic predisposition to a particular disease.Using data from the UK Biobank, the team estimated that the average person ranked in the top 10% for genetic risk for nearly three of the 28 common conditions studied. Around one in five people ranked in the top 1% for at least one of the polygenic risk scores examined.A high ranking does not provide a definitive prediction of an individual’s future health. Rather, it indicates that their genetic profile is associated with a higher relative risk compared with the population used to calculate the score.
Why the findings matter as genetic testing expands
Whole-genome sequencing is increasingly being used to help diagnose genetic conditions, while genetic screening is also being explored as a way to assess future disease risk.However, interpreting the results can be challenging when people discover variants associated with illnesses they do not have. The study offers a broader picture of how much genetic variation is present in the general population and why genetic findings need to be considered in context.Senior author Caroline Wright of the University of Exeter said that people are often unaware of the extent of genetic variation in their DNA.“Actually, variation is the norm,” Wright said, according to PTI.She added that the study could help doctors and patients understand and interpret genetic findings more accurately.Wright also stressed the importance of considering symptoms, family history and other clinical and environmental risk factors when interpreting genetic test results. This context is particularly important when genetic screening identifies a potential risk in someone who appears healthy.
What should people take away from the study?
The findings are not a reason to assume that everyone is on the path to developing diabetes, cardiovascular disease or schizophrenia. They instead underline how common genetic differences are, including variants associated with disease.A genetic risk score is one piece of information, not a diagnosis. It should not be interpreted in isolation or used to predict an individual’s future with certainty.As genetic testing becomes more widespread, the challenge for doctors and patients will be to distinguish between a statistical predisposition and a meaningful personal health risk. The study’s central message is that genetic variation is common, but its implications depend on context.
