[Physician or seer? Very early diagnosis and prognosis. The example of William's syndrome].

Recent major breakthroughs in the field of genetics have allowed very early diagnosis of many genetic diseases. This is usually considered as beneficial progress. But is it that simple? Which information is given to the parents? How useful is it? And for whom? How will it influence the child's development? The case of three children with Williams' syndrome and the current knowledge on the cognitive and behavioural phenotype of this syndrome provide food for thought on these questions. Answers can be neither unique nor final. The purpose is not to deny present knowledge or tomorrow's discoveries, but rather to take time to think about the consequences of a very early diagnosis announcement, particularly the anticipation of the handicap that it carries.