Gamma-glutamylcysteine synthetase deficiency is 1 of 4 diseases involving enzymes in the gamma-glutamyl cycle (Meister, 1974). The other 3 disorders are glutathione synthetase deficiency (231900), 5-oxoprolinuria, which is a severe or generalized form of glutathione synthetase deficiency (266130), and gamma-glutamyl transpeptidase deficiency (231950). All except gamma-glutamyl transpeptidase deficiency are accompanied by hemolytic anemia (Larsson and Anderson, 2001). Some patients with CNSHA7 may develop progressive neurologic abnormalities, including ataxic gait, speech impairment, and spinocerebellar degeneration (Konrad et al., 1972). The hemolytic anemia caused by mutation in the GCLC gene is here designated congenital nonspherocytic hemolytic anemia-7 (CNSHA7).