Pallister Killian--mosaic tetrasomy 12 p syndrome. Another prenatally diagnosed case.

A new case of mosaic tetrasomy 12 p (46,XY/47,XY, +i12 p), diagnosed during pregnancy from ultrasonographic signs, is reported. We emphasize the peculiar position of the diaphragmatic hernia in this syndrome. Its presence or absence determines the vital prognosis and the age of diagnosis. The knowledge of its possible association with tetrasomy 12 p can contribute considerably to the neonatal diagnosis by directing the work of the cytogeneticist to tissue cultures which enable him to detect the presence of the tetrasomy.