First trimester studies of a fetus at risk for triose phosphate isomerase deficiency.

A first trimester prenatal diagnosis was offered to a mother whose child had died of haemolytic anaemia and multisystem disease caused by TPI deficiency. The deficiency state was characterized by greatly reduced TPI activity in both erythrocytes and peripheral lymphocytes. Specific activity of TPI in trophoblast homogenates from the index fetus was about 30 per cent less than in the controls, but the heat stability test showed overlap. These data were confirmed in uncultured and cultured amniotic cells, where glycolytic intermediate concentrations DHAP, GAP and FDP fell in the range of controls. These results suggested that the fetus was a TPI heterozygote. This prenatal prediction was confirmed by RBC and haematological studies at birth.