WHAT HAS CHANGED IN GENETICS IN THE LAST 10 YEARS

Key words: Clinical Genetics, Syndromes, Genetic counselling

The recent developments of genetics allow a clearer diagnosis of most of the syndromes and diseases due to defects of the genetic code and of the chromosomal pattern. New techniques such as FISH (Fluorescent in Situ Hybridization) and CGH-microarrays (Comparative Genomic Hybridization) may help to define those syndromes with submicroscopic abnormalities which cannot be diagnosed by standard cytogenetic analyses. In addition, such techniques may find subtelomeric rearrangements responsible for mental retardation and malformations with sporadic occurrence and without elements recalling any known syndrome (about 7% of severe mental retarded children show a telomeric defect). Syndromes with abnormalities of genetic mechanisms without mendelian inheritance may be diagnosed with DNA and cytogenetis procedures, showing for example defects of genomic imprinting, uniparental disomies, dynamic mutations with trinucleotied amplification. Prenatal diagnosis and therefore genetic counselling to couples and families may be influenced by the application of these new techniques