Medical Care
Protein intake is restricted in patients with arginase deficiency. A carefully monitored diet plan is necessary.
Because severe hyperammonemia is unusual, the need for intravenous therapy or hemodialysis is unlikely. In the event that intravenous therapy or hemodialysis is required, the need to omit intravenous arginine from the treatment regimen should be obvious.
Long-term therapy rests on provision of a low-protein diet and, possibly, oral sodium benzoate or sodium phenylbutyrate. A recent report suggests that glycerol phenylbutyrate supplies a more extended scavenger effect [12] ; this deserves further evaluation, as it could provide for an improvement in quality of life for affected individuals. A metabolic disease expert should guide the treatment of this rare condition.
A 2016 demonstration of arginase-1 activity restoration via gene manipulation to patient-specific arginase-1–deficient pluripotent stem cells offers the possibility of correction of the hepatic defect in humans. However, clinical trials have yet to be reported. [13]
Surgical Care
As has been the case for several years with all urea cycle disorders, orthoptic liver transplantation has been advocated as a definitive cure for arginase deficiency. In a recent report of long-term follow-up of 2 arginase-deficient patients, Silva et al claim the arrest of neurological progression without dietary restrictions. [14] Since the disorder is so uncommon, it is difficult to verify such claims based on a large patient series.
Consultations
See the list below:
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Medical geneticist
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Metabolic disease specialist
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Dietitian
Prevention
Prenatal diagnosis can be performed using DNA analysis.
Recent experience with tandem mass spectrometric newborn screening technique has permitted early identification and treatment. Infants treated in this fashion have thus far done well and remained healthy.
Further Outpatient Care
A biochemical geneticist, a metabolic disease specialist, or both should guide the management of arginase deficiency, as with all urea cycle disorders. [15]
Nutritional management is the mainstay of treatment and should be carried out under the scrutiny of a highly trained nutritionist.
Closely monitor affected individuals for growth and plasma amino acid levels; under no circumstances should a child with arginase deficiency be cared for by a primary care provider alone.
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Compounds that comprise the urea cycle are sequentially numbered, beginning with carbamyl phosphate (1). At this step, the first waste nitrogen is incorporated into the cycle; N-acetylglutamate exerts its regulatory control on the mediating enzyme, carbamoyl phosphate synthetase (CPS), in this step. Compound 2 is citrulline, the product of condensation between carbamyl phosphate (1) and ornithine (8); the mediating enzyme is ornithine transcarbamylase. Compound 3 is aspartic acid, which is combined with citrulline to form argininosuccinic acid (ASA) (4); the reaction is mediated by ASA synthetase. Compound 5 is fumaric acid generated in the reaction that converts ASA to arginine (6), which is mediated by ASA lyase.
