Advances in genetics and technology now allow us to identify predispositions to certain diseases. What are the real benefits of knowing your genetic vulnerabilities, and what risks should we guard against? High-throughput genome sequencing technologies can now rapidly analyze the DNA in our 70 trillion cells, opening the door to personalized predictive medicine. These tools reveal gene mutations that may lead to serious diseases.
Interpreting these results accurately is crucial, as a risk factor doesn't guarantee disease onset. For the data to be actionable, effective prevention or early intervention strategies must follow. In France, genetic testing is tightly regulated, but elsewhere, DNA analysis has become a profitable industry with ethical concerns.
"Over 8,000 diseases linked to single-gene anomalies have been identified," notes Professor Pascal Pujol, president of the French Society of Predictive and Personalized Medicine (SFMPP) and author of Do you want to know what our genes say about our health? (ed. Humen Sciences).
Rarely does a genetic anomaly guarantee disease development. Huntington's chorea, causing neurological degeneration from age 30 or earlier with no current treatment, is one exception. In at-risk families, prenatal screening is offered since inheriting one faulty gene copy inevitably leads to the condition.
Video of the day:
In most cases, genes interact with environmental factors, gut flora, and lifestyle. A predisposing gene indicates elevated risk compared to the general population, not certainty. Conditions like diabetes, common cancers, and autoimmune diseases are multifactorial.
When multiple family members develop early breast cancer, BRCA1 or BRCA2 mutations—which normally repair damaged DNA—may be involved. Women can access genetic testing through oncogenetic consultations.
Carrier status informs targeted prevention. In 2013, Angelina Jolie opted for preventive double mastectomy, followed by ovary and fallopian tube removal in 2015.
"BRCA1 confers a 70% breast cancer risk and 30% ovarian cancer risk," explains Professor Pujol. Not all carriers develop cancer, so alternatives include annual (or bi-annual from age 30) screening. Ovarian screening is challenging, so post-childbearing preventive surgery may be recommended.
Developed by Predilife (a Gustave Roussy Institute spin-off), Mammorisk evaluates breast cancer risk from age 40 using clinical data, imaging, and genetics. Doctors tailor 5-year screening plans based on the score.
Available at Paris Breast Institute, Santa Maria Institute in Nice, and American Hospital of Neuilly/Seine, it's ideal for women under 50 outside national screening. It also promotes lifestyle changes like weight control, quitting smoking, and exercise, which significantly lower risks—especially for high-genetic-risk individuals.
Similarly, newborn screening for MCAD deficiency (now added to five others) enables prevention through diet, averting complications like developmental issues or sudden infant death syndrome.
Often, predictions cause unnecessary anxiety without actionable steps. Many susceptibility genes are non-specific or remain dormant lifelong.
A genetic variant appears in 80% of celiac disease patients but also in many healthy people—a nuance ignored by commercial tests.
In France, tests require medical prescription or court order via approved labs. Elsewhere like the US, UK, and Brazil, they're direct-to-consumer.
Nearly 100 million people worldwide have used them (MIT Technology Review). Despite €3,750 fines in France, over 100,000 French users buy online for ancestry, cancer, Alzheimer's, or diabetes risks—via mail-in saliva swabs.
"These tests lack reliability and medical follow-up," warns Professor Pujol.
"Recreational" tests transfer your full genome to private firms. EU GDPR protects data, but not always abroad. Contracts often allow resale to pharma companies.
Hacks, like MyHeritage's, expose data. If accessed by insurers or banks, it could affect loans or premiums. Ethical risks abound.
* Available on Place des libraires and Amazon.
Read also: