The role of pathology in prenatal diagnosis.

Antenatal diagnosis of hereditary disease is highly dependent on sufficient theoretical knowledge and on a number of practical methods of studying the foetus such as obtaining, cultivating and assaying amniotic fluid cells. Knowledge of the primary defect in any monogenic disorder cannon be used in prenatal diagnosis unless the metabolic error is expressed in vitro. Modern cytogenetics can diagnose in utero a large majority of karyotyping abnormalities although the karyotype-phenotype correlation is not an absolute one. This task must be assigned to special laboratories where technical pitfalls are reliably avoided. In both metabolic and chromosomal hereditary disease, the pathologist can confirm and extend the phenotypic findings and improve knowledge on foetal features and physiopathology. Pathology is the more important, the less means of in utero diagnosis are available as in the non-chromosomal syndromes of localized or multiple malformations. Here it helps eliminating a present major drawback of prenatal diagnosis: the lack of a strict diagnosis in the previous patient in a family at risk.