... deficiency of early and late onset. J Pediatr 101 :54 6 -5 50 5. Suormala T, Fowler B, Jakobs C et al (1998) Late-onset holocarbo-xylase synthetase-deficiency: pre- and post-natal diagnosis and evaluation ... precursor, 4-imidazolone -5 - propio-nate and 4-amino -5 - imidazolecarboxamide, an interme-diate of purine synthesis. Treatment and PrognosisIt is not clear whether reducing formiminoglutamate ex-cretion ... formation of 5- oxoproline exceeds the capacity of 5- oxoprolinase. Therefore, 5- oxo-proline accumulates in the body fluids, causing metabolic acidosis and 5- oxoprolinuria. The level of J-glutamylcysteine...