Neurodegenerative diseases, such as Alzheimer's dementia, Huntington's chorea, Parkinson's disease or spinocerebellar ataxia, manifests into adulthood with an insidious onset, slowly of progressive symptoms. All of these diseases are characterized by presimptomatic stages that preceded with many years of clinical debut. In Parkinson's disease, more than half of the dopaminergic neurons of the black substance are lost before the advent of motor characteristic manifestations. In Huntington's chorea, the progressive neurodegenerative disease could be diagnose prenatal and presymptomatic by analyse of the number of CAG repeats in exon 1 of the huntingtin gene. A similar mechanism represented by expansion of trinucleotide repeats during hereditary transmission from parents to children was identified in fragile X syndrome, spinocerebellar ataxia, spinal muscular and bulbar atrophy, or myotonic dystrophy. Presymptomatic diagnosis in all these progressive diseases raise many ethical issues, due to the psychological impact that can cause the prediction of a disease for which there is currently no curative treatment. Therefore, a positive result can produce serious psychological trauma and major changes in the lifestyle of the individual, instead, a negative result can bring joy and tranquillity. But the problem arises if presymptomatic testing in these neurodegenerative diseases brings greater benefits compared to the possible psychological damage, which can add the risk of stigmatization or discrimination.