Polygenic risk scores are becoming more accurate and help identify people more prone to diseases such as cancer and Alzheimer’s. But they are not exempt from doubts about their reliability or their ethics. Who would want to know that they are going to suffer from a disease that has no cure?

As the cardiologist explains how his disease prediction work works, his hands float in the air to arrange invisible columns representing groups of people. There’s the column of 30,000 people who have had heart attacks, another with 10,000 healthy control subjects, and so on.

The world has never had as much genetic information about people as it does now. And this wealth of information means that researchers are able to predict a person’s chance of developing diseases such as diabetes, arthritis, clogged arteries, and depression.

Doctors are already testing for mutations in individual genes that cause deadly diseases. Think of the BRCA gene associated with breast cancer or the one-letter mutation that causes sickle cell anemia. But the most common ailments are not associated with a mutation in a single gene. Instead, they have more complex causes that, until now, have not been identified.

The day I visited him, he was building what is now known as the polygenic risk score. The prefix “poly” refers to the fact that these scores depend on thousands of genes, not just one. The score Khera was working on at the time predicts how likely a person is to develop atrial fibrillation. Although it is the most common form of arrhythmia, it is often not diagnosed until the patient is admitted to the emergency room with a stroke.

The breakthrough: a new way to predict the possibility of suffering from a serious disease from DNA. Disadvantages? Technology could lead to a society that classifies people based on their intellectual abilities from birth.

Khera points to her screen, which shows seven digital numbers, each representing the score of an anonymous DNA donor. The outliers showed a risk four times greater than the average. These new scores make it possible to identify both the risk of certain diseases and the rare genetic defects that are of great concern to doctors.

I think eventually we will get younger patients to receive a report on their DNA that will tell them their score for these 10 diseases. You are in the 90% range of having heart disease, 50% of having breast cancer, and the lowest, 10%, of having diabetes.

These comprehensive reports are not yet being produced, but the science to create them is already available. By delving into large databases like the UK Biobank (which collects the DNA of some 500,000 Britons and stores medical records) geneticists can dig into more people’s lives to look for correlations between their genomes and the diseases they cause. they suffer from, their personalities and even their habits. The latest genetic hunting feat, focused on looking for the causes of insomnia, has broken a record with its more than 1.3 million people involved in the study.

This enormous amount of information is what allows scientists to analyze how different variations of complex genetic patterns are related to many diseases and traits. These patterns were hidden in previous smaller studies, but now the search for small signals in larger trials is bearing fruit….