Glutathione synthetase (GS) deficiency (oxoprolinuria) is a rare autosomal recessive disorder affecting about 70 patients in the world. Patients with severe GS deficiency show, among other conditions, an increased susceptibility to bacterial infections. 5, 6 One case report showed that neutrophils from a child with GS deficiency undergo oxidative damage upon phagocytosis, indicating that GSH is important in defending the neutrophils from the ROS they produce as part of their microbicidal armamentarium. 7 Of note, neutrophils from GS-deficient patients, despite normal phagocytosis and increased release of hydrogen peroxide, are less efficient in killing bacteria, indicating a helper role for GSH in the bactericidal activity. 8