[Implications for genetic counselling in regard to sex chromosome aneuploidies diagnosed by amniocentesis (author's transl)].

It is in the detection of chromosomal aneuploidies that amniocentesis currently renders the greatest service. However, when an anomaly of the fetal sex chromosomes is found, the decision of what attitude to hold in counselling the parents poses a real dilemma, due to the importance of phenotypic variation-notably of intelligence and behavior-in individuals with sex chromosome disorders. It is in such situations that the need for information furnished by prospective studies is particularly evident. Prenatal diagnosis of four cases of sex chromosomal polysomy, detected in the course of approximately 600 amniocenteses, is presented, as are the criteria which may guide the parents in their decision to continue or to terminate a pregnancy so affected.