How is the early diagnosis of genetic diseases usually done?
Genetic disease might be diagnosed in the prenatal period by karyotype analysis, in case of aneuploidies, or by DNA analysis, in case of other diseases.
The test is done by removal of material containing cells of the embryo by amniocentesis (extraction of amniotic fluid) or cordocentesis (puncture of the umbilical cord) or even by chorionic villus biopsy.