Arginase Deficiency Presenting as Intractable Hiccups With Severe Hyperammonemia at One Month of Age

Abstract

Arginase deficiency is a rare urea cycle disorder and generally presents in children of preschool age with developmental delay and spasticity. Unlikely other urea cycle defects, patients rarely present hyperammonemic symptoms, especially in the early infantile period. A one-month-old male infant was admitted to our hospital because of abnormal respiratory condition with persistent hiccups and lethargy. The initial laboratory studies showed respiratory alkalosis and remarkable hyperammonemia [ammonia, 1970 ? mol/L (25 times normal)]. Amino acid chromatography showed a markedly elevated plasma arginine level (1131 µ mol/L; 10 times normal), and erythrocyte arginase activity was undetectable. Despite prompt diagnosis and normalization of ammonia and arginine levels by peritoneal dialysis, the patient developed neurodevelopmental impairment during the one-year follow-up period. In summary, this is a rare case of arginase deficiency in terms of early infantile onset and presentation of the severe form of hyperammone mia. Pathologic hiccups could be one of the clinical clues to the presence of hyperammonemia even in young infants with arginase deficiency. doi:10.4021/jmc141w