Prenatal diagnosis and fetal pathology of Tay-Sachs disease.

In 6 cases of high risk pregnancies for Tay-Sachs disease, prenatal diagnosis was successfully carried out by examining hexosaminidase A activity in the supernatant of amniotic fluid and the uncultured and cultured amniotic fluid cells. In 5 out of 6 cases, the activity of hexosaminidase A was found to be within normal or heterozygous levels. They continued their pregnancies and were delivered of healthy children. In the remaining 1 case, the activity was undetected. Her pregnancy was terminated at the 23rd week of gestation. There was no activity of hexosamindase A in the brain and liver from the aborted fetus. A moderate increase in GM2 ganglioside was found in the brain. Electron-microscopic findings revealed membranous cytoplasmic bodies in the spinal ganglion cells as well as in the nerve cells of the retina. These biochemical and histological findings of Tay-Sachs fetus suggest that the disease proceeds early in fetal period. It was found that the cultured amniotic fluid cells was the most reliable material for the prenatal diagnosis of Tay-Sachs disease, because the values of hexoxaminidase A in the cultured cells were well in accord with those in serum from the consequently bord children. Hexosaminidase pattern in the supernatant of amniotic fluid on DEAE-cellulose columnchromatogram showed a distinct difference between homozygote, heterozygote and normal. This procedure also may be useful for prenatal diagnosis of Tay-Sachs disease.