The genetic adviser can be a pediatrician, an obstetra, a familiar doctor, a nurse or a specialist in genetics, who obtains the familiar history and realizes a physical examination of the parents and biological children. Laboratory tests can be practised in blood, skin, urine or fingerprints. It is possible to analyze and to photograph the chromosomes of the corporal textiles, extracting the cariotipo. This picture can show the chromosomal abnormalities and indicate if a seemingly normal person might transmit congenital defects to a child. The adviser tries to help the clients to understand the mathematical risk of a particular condition, tells his implications and presents the information about the alternative courses of action.

The geneticists have done big contributions to avoid the genetic defects. For example, because the genes of the illness of Tay-Sachs have been analyzed in multiple Jewish couples, a greatly minor number of children has been born with this illness. Today it is much more probable that this illness affects not Jewish child. Something similar happens in the Mediterranean countries with the beta talasemia.