PRENATAL MOLECULAR DIAGNOSIS OF RET PROTOONCOGENE MUTATION IN MULTIPLE ENDOCRINE NEOPLASIA TYPE 2A

We report a case of multiple endocrine neoplasia type 2A (MEN 2A) diag nosed prenatally at 16 weeks gestation. The 35-year-old mother is a ME N 2A patient. She had had three prior pregancies: one resulted in a st illbirth; one produced a genetically unaffected boy; and the third was terminated in the first trimester owing to a diagnosis of blighted ov um. Autopsy did not reveal the cause of death of the stillborn infant, who was also found to be affected with MEN 2A by molecular study of p araffin-embedded tissue. Because of poor obstetric history and the pat ient's age, amniocentesis for cytogenetic and molecular studies was pe rformed at 16 weeks' gestation during the pregnancy under discussion. As with other affected members in the mother's family, the missense mu tation of TGC to TTC at codon 634 of the RET proto-oncogene was found in amniotic fluid cells. Analysis of DNA extracted from the lymphocyte s of the infant's blood at birth confirmed the diagnosis. To our knowl edge, this is the first report of prenatal diagnosis of MEN 2A.