Daijiworld Media Network - London
London, Oct 25: An average person may rank among the 10 per cent of people with the highest genetic risk for nearly three common diseases, including diabetes, cardiovascular disease and schizophrenia, according to a new study led by researchers at the University of Exeter in the United Kingdom.
The study, published in the journal *Genome Medicine*, highlights the widespread genetic variations among humans and the challenges of interpreting genetic test results, particularly when people who appear healthy discover that their DNA is associated with an increased risk of certain diseases.
Researchers found that the average person ranked in the top 10 per cent for genetic risk for nearly three of the 28 common conditions examined. Around one in five people ranked in the top one per cent for at least one of the polygenic risk scores assessed.
The findings do not mean that these individuals will necessarily develop the diseases. Instead, they indicate that their genetic profiles are associated with a higher relative risk compared with the population used to calculate the scores.
**The study found that every person's genome contains approximately five million genetic variants, or DNA locations that differ between individuals.** While many of these variations have little or no known impact on health, others can influence physical traits and biological processes, including lactose intolerance and how the body 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 approximately 50 rare variants whose clinical significance remains uncertain.
To assess the prevalence of genetic susceptibility, the researchers examined polygenic risk scores, which 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 assessed genetic risk across 28 common conditions. The results showed that high genetic risk scores are relatively common in the general population, even among people who have no symptoms or apparent signs of disease.
The researchers said the findings are particularly relevant as whole-genome sequencing becomes increasingly common in the diagnosis of genetic conditions and genetic screening is explored as a means of assessing future disease risks.
Interpreting such results can be challenging when individuals discover genetic variants associated with illnesses they do not have. The study provides a broader understanding of the extent of genetic variation in the population and underscores the need to interpret genetic findings in the appropriate clinical context.
Senior author Caroline Wright of the University of Exeter said 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 findings could help doctors and patients better understand and interpret genetic test results.
Wright also emphasised the importance of considering symptoms, family history and other clinical and environmental risk factors when assessing genetic findings. This is particularly important when screening identifies a potential genetic risk in someone who appears healthy.
The researchers stressed that the findings should not be interpreted as suggesting that everyone is likely to develop diabetes, cardiovascular disease, schizophrenia or other common conditions. Rather, they highlight how widespread genetic differences are, including variations associated with diseases.
A genetic risk score is one component of an individual's overall health profile and is not a diagnosis. It cannot, on its own, determine whether a person will develop a particular condition.
As genetic testing becomes more widespread, the challenge for healthcare professionals and patients will be to distinguish between a statistical predisposition and a meaningful individual health risk. The study's central message is that genetic variation is common, but its implications depend on the wider clinical and environmental context.