GCLC and Adult onset: γ‐Glutamyl‐cysteine synthetase (GCLC) catalyses the conjugation of glutamate and cysteine to γ‐glutamyl‐cysteine and is the first and rate‐limiting step of glutathione biosynthesis.77 GCLC deficiency leads to extremely low levels of erythrocytic glutathione and γ‐glutamyl‐cysteine which result in infantile‐adult onset haemolytic anaemia.78 Other reported features are neurological problems, amino aciduria, reticulocytosis, and hepatosplenomegaly with transient jaundice but whether these are related to the enzyme defect remains unclear.79, 80, 81