A new variant of glucosephosphate isomerase deficiency: GPI-Kortrijk.

A new case of glucosephosphate isomerase deficiency in a Belgian family is described. The activity of the enzyme was decreased to about 25-30% of the normal value. Characterization of the defect enzyme showed a decreased thermostability. Heating of the enzyme at 45 degrees C showed a loss of activity of 50% after 90 min. The pH-optimum and the KM-value for fructose 6-phosphate were normal. The electrophoretic pattern showed a faster migration. The variant described here differs from all known variants. Therefore we propose to give to this new variant the name GPI-Kortrijk.