Neurofibromatosis type 1 (NF1) is an autosomal dominant inherited disease of genetic origin. It is one of the most common genetic diseases affecting between 1 in 3,000 and 6,000 births.
As part of the referral centre, we offer genetic counselling interviews for all patients, but also genetic consultations, sometimes necessary as part of the diagnostic process ("atypical" neurofibromatosis).
The risk of transmission of the disease to offspring is 50%. However, since the expression of the disease varies within the family, it is impossible to anticipate the severity of the phenotype.
Prenatal Diagnosis (PND) or Pre-Implantation Diagnosis (PGD) techniques are currently possible, whether it is a familial form (several affected people in the same family) or a sporadic form of the disease (only one person affected), provided that the molecular abnormality responsible for NF1 has been identified beforehand.
Non-Invasive Prenatal Diagnosis (NIPT) can now be proposed when the molecular abnormality sought in the foetus is of paternal origin and is a point mutation.
Transmission of NF1 - Example of a family tree where the father has NF1, and the mother is unharmed.
The geneticist, or genetic counsellor, receives you in a genetic counselling interview to provide you with appropriate information on the genetic nature of your disease.
Genetic counselling is often offered in the following 3 situations:
- Following the announcement of the diagnosis concerning you or your child.
- Prior to the prescription of the genetic test. You are given clear and appropriate information about the disease, the purpose of the genetic test, the personal and family consequences of the result, and the right not to use genetic testing. The result of the genetic analysis is given in the context of an individual consultation.
- Upstream of a parental project to inform you about the possibilities of using a Prenatal Diagnosis (PND), a Pre-Implantation Diagnosis (PGD), or a Non-Invasive Prenatal Diagnosis (NIPT), under certain conditions.
Genetic counselling allows patients to make an autonomous and informed choice about whether or not to use one of these diagnoses.
Genetic consultations are provided by a medical geneticist at the request of your doctor. They can also include the intervention of a genetic counsellor, working under the responsibility of the doctor.
The geneticist works in collaboration with doctors at the neurofibromatosis referral centre to identify the genetic cause of your disease.
The geneticist prescribes genetic tests and sees you again in consultation to explain the results. A clinical examination can occur during the consultation, and photographs may be taken in case they are useful for the diagnosis.
The geneticist and the genetic counsellor are always interested in your family history. It is not necessary to prepare a family tree, but they will ask questions about the health of your loved ones (parents, uncles and aunts, brothers, sisters, and their children, cousins) including a disability, a genetic disease, malformations, etc. Any questions that will clarify genetic counselling, particularly when deciding to become a parent.
If you have already had a sample for a genetic analysis, it is necessary to come with the result of the genetic analysis or the date of the collection as well as the name of the prescribing doctor of the genetic analysis.