Ophthalmological, psychometric and therapeutic investigation in two sisters with hereditary glutathione synthetase deficiency (5-oxoprolinuria)

Two sisters with hereditary glutathione synthetase deficiency (5-oxoprolinuria) were investigated. Assays of erythrocyte enzyme levels in relatives revealed additional clinically healthy carriers. The girls had chronic metabolic acidosis, which was corrected by substitution with bicarbonate. They had an increased rate of hemolysis which was well compensated. Their granulocyte function was normal when tested in vitro. In both girls mental retardation developed progressively without additional clinical neurological symptoms. Their electroretinograms were abnormal indicating disturbed retinal electrophysiological function. Therapeutic trials were performed with oral administration of glutathione (Tathion), mercaptopropionylglycine (Thiola) and vitamin E. None of these compounds had an effect on the urinary excretion of 5-oxoproline, acid-base balance, pathological electroretinograms or the clinical condition. Initially, Thiola therapy increased the low levels of glutathione in patient erythrocytes but after several months of treatment the concentration of glutathione declined to pretreatment levels. There was no indication that orally administered glutathione, mercaptopropionylglycine or vitamin E had a beneficial effect in the doses used. Nevertheless, vitamin E administration has been continued in addition to the correction of acidosis with sodium bicarbonate.