Genetics is a medical specialty dedicated to research into genetic diseases and heredity. It is aimed at patients of all ages (from the antenatal period to adulthood) and is at the interface with other medical specialties, in particular the pediatrics,oncology, Or the neurology.

Remember that each individual has 23 pairs of chromosomes, which carry the genetic information necessary for the development and functioning of the human body. In some cases, the letters that make up this genetic code may contain “errors”, which can lead to dysfunction or malformation. It can be a mutation (replacement of a “letter” by another), a deletion (disappearance of a part of a chromosome, for example), a trisomy (supernumerary chromosome), etc.

There is a wide variety of genetic diseases, which can manifest from birth or later in life with a multitude of symptoms. In total, there are more than 6 diseases linked to a genetic defect.

Medical genetics can be broken down into several sub-specialties:

• oncogenetics, which focuses on the risks of cancer of genetic origin and prevention in families (reinforced monitoring, preventive surgery, etc.);
• clinical genetics, which involves diagnosing rare diseases suspected of having a genetic origin and counseling affected families;
• molecular genetics and cytogenetics, which consist of developing diagnostic tests, identifying new genetic mutations, offering prenatal (high-risk pregnancy, abnormalities identified after amniocentesis, etc.) and postnatal (mental retardation, malformations, etc.).

Note that in some hospitals in France, genetic counselors (non-doctors) can also offer genetic consultations, produce family trees and explain the risks to patients (in collaboration with a geneticist).

The geneticist can diagnose or manage many conditions. As we have seen, there are thousands of possible genetic pathologies, most often rare (affecting less than one in 2 people, by definition). Among the most frequent:

• la cystic fibrosis (or cystic fibrosis);
• thehemochromatosis ;
• la trisomy 21 (or Down syndrome);
• myopathies (genetic diseases affecting the muscles), such as Duchenne muscular dystrophy ;
• the breast cancer linked to a mutation of the BRCA1 or BRCA2 genes;
• thehaemophilia ;
• sickle cell anemia or sickle cell anemia;
• thalassemias (diseases of the red blood cells);
• Huntington’s chorea;
• fragile X syndrome.

When a family member has a genetic disease, the risks to offspring or siblings are potentially higher. Genetic counseling can make it possible to assess these risks, and in particular to advise parents who already have an affected child. Depending on the disease, the risks that the second child will also be sick vary, ranging from 0 (no recurrence) to 50% (a disease known as autosomal dominant transmission).

Symptoms of genetic diseases can be extremely varied, and can be seen from birth (sometimes even prenatal on ultrasound) or appear in childhood or adulthood. Some signs that may indicate a genetic disease include:

• dysmorphisms (deformation of one or more organs or of the face);
• metabolic abnormalities;
• intellectual deficits;
• neuro-muscular disorders;
• cancers occurring early or affecting several people in the same family, etc.

The role of the geneticist is:

• assess patients (children or adults) in case of suspected genetic disease to make a diagnosis and ensure follow-up;
• to meet with the family to try to understand the cause of the disease (genetic tests, study of the family tree, etc.);
• to determine whether or not the disease is hereditary (is it transmissible? what are the risks for the offspring or siblings?);
• study chromosomes to find the offending gene or mutation;
• to advise families with one or more members suffering from a genetic anomaly for pre and post-natal follow-up (family screening, prenatal and pre-implantation diagnosis, presymptomatic diagnosis, risk assessment).

To diagnose a genetic disease, the geneticist can rely on clinical signs and can confirm his hypothesis by performing a genetic analysis (which is done from a blood or skin sample, from a prenatal examination, etc.).

The consultation with a geneticist does not involve any particular risks for the patient. In the case of prenatal examinations aimed at looking for a genetic abnormality in the fetus during pregnancy (amniocentesis or chorionic villus sampling), there is a risk of miscarriage generally assessed at 1/100.

Training as a geneticist in France       

To become a geneticist, the student must obtain a Diploma of Specialized Studies (DES) in medical genetics (clinical, chromosomal and molecular) 3:

• he must first follow, after his baccalaureate, a common first year in health studies;
• then 6 years of medical studies;
• at the end of the 6th year, students take the national classifying tests to enter the boarding school. Depending on their classification, they will be able to choose their specialty and their place of practice. The medical genetics internship lasts 4 years (3 genetics internships – clinical genetics, cytogenetics, molecular biology -; a compulsory pediatrics internship and 4 free internships).

Finally, to be able to practice and carry the title of doctor, the student must also defend a research thesis.

Note that a master 2 is generally carried out during an internship in parallel to develop the research aspect.

Training as a geneticist in Quebec

After college studies, the student must:

• follow a doctorate in medicine, lasting 1 or 4 years (with or without a preparatory year for medicine for students admitted with a college or university training deemed insufficient in basic biological sciences);
• then specialize by following a residency in medical genetics for 5 years.

Before going to an appointment with a geneticist, it is important to learn about their family tree and the health status of family members to find out if other people have or were having similar symptoms.

To find a geneticist:

• in Quebec, you can consult the website of the association of geneticists of Quebec4, which offers a directory of its members;
• in France, via the Orphanet5 website, a portal dedicated to genetic diseases and rare diseases, which offers a list of genetic consultations and a multitude of resources. There are “referral” medical centers for most rare diseases, to which patients are referred.

When the consultation with the geneticist is prescribed by an attending physician, it is covered by the Health Insurance (France) or the Régie de l’assurance maladie du Québec.