The main contribution that medical genetics makes to the work of a general practitioner is in the identification and characterisation of the role of genetic variations and mutations relating to the causes of several hundred diseases.

The Medical Genetics Department of the Central Institute of hospitals carries out laboratory analyses and provides specialist medical advice.

There are three categories of diseases which arise mainly on account of genetic factors:

• Monogenic diseases, in which an anomaly in a single gene is responsible for the condition (e.g.: cystic fibrosis, neurofibromatosis, Marfan’s syndrome)
• Chromosomal diseases, which arise out of the excess or loss of the genes carried by a fragment of chromosome or by a complete chromosome. Such anomalies are in particular responsible for numerous cases of mental disability and for almost half of the spontaneous abortions that are observed during the first trimester of pregnancy
• Multifactorial hereditary diseases, which arise out of the combined effect of several genetic variations together with various environmental factors. It is estimated that such situations have a major impact on the health of over 60% of the European population

It should be stressed that any request made by a doctor for a molecular genetics analysis implies that this doctor is aware of the indications for such an analysis and is able to appreciate the predictive value of its results. By issuing a request for this type of analysis, the doctor thus acknowledges that he/she has provided his/her patient with appropriate genetic advice and has discussed the conditions for its costs being covered by the patient’s health insurance. Genetic analyses are in principle only permitted on adult patients who have given their consent. The Federal Law on Human Genetic Analysis (‘Loi fédérale sur l'analyse génétique humaine’, LAGH) furthermore requires that any pre-symptomatic genetic analysis that is carried out within the framework of prenatal diagnosis or with the aim of determining a (healthy) carrier state, be preceded and followed by genetic consultations, that written consent be provided by the patient, and that the consultations be co-signed.