Prenatal exclusion of Pompe disease by electron microscopy.

Pompe disease is a lysosomal storage disorder caused by alpha-glucosidase deficiency. The disease is characterized by accumulation of glycogen in the lysosomes. The accumulation has unique ultrastructural features which enable a prenatal diagnosis by electron microscopy. We describe prenatal electron microscopic testing in a fetus of a mother whose previous child died of Pompe disease. The disease in the affected child was diagnosed by a decrease in alpha-glucosidase activity of his skin fibroblasts. Electron microscopy of the chorionic villus sample and amniocytes revealed normal findings, thus predicting an unaffected fetus. The study was confirmed by the birth of a normal neonate who was still healthy at the age of 12 months. Electron microscopy is useful in the first and second trimesters to exclude Pompe disease prenatally. This test can be use prenatally and provides families with reassurance.