Disorder Factsheet for Professionals

Amino Acid Disorders

Disease Name	Argininemia/ arginase deficiency
Alternate name(s)	Hyperargininemia ARG I Deficiency
Acronym	ARG I
Disease Classification	Amino Acid Disorder
Variants	Yes
Variant name	ARG II
Symptom onset	Primarily neonatal but also infancy and childhood
Symptoms	Spastic diplegia or tetraplegia, opisthotonos, seizures, acquired microcephaly, hepatomegaly, vomiting, anorexia and irritability. Coma and death due to hyperammonemia have been reported.
Natural history without treatment	Developmental delay due to hyperargininemia or hyperammonemia. Neurologic damage can include spasticity, hyperactivity, ataxia, seizures and cerebral atrophy.
Natural history with treatment	If treatment occurs prior to catastrophic hyperammonemia, normal outcome is possible but not proven. Treatment can decrease some of the neurologic symptoms but complete reversal is not likely.
Treatment	Dietary restriction of arginine, protein restriction and supplementation of amino acids other than arginine. Sodium benzoate therapy.
Other	Spastic diplegia or tetraplegia
Physical phenotype	No physical dysmorphisms but may be thought to have cerebral palsy
Inheritance	Autosomal recessive
General population incidence	Rare (1:300,000)
Ethnic differences	No
Population	N/A
Ethnic incidence	N/A
Enzyme location	Liver and erythrocytes
Enzyme Function	Terminal enzyme of the urea cycle which hydrolyzes arginine to urea and ornithine to dispose of excess nitrogen
Missing Enzyme	arginase
Metabolite changes	Increased arginine in plasma, urine and cerebrospinal fluid. Increased amino acids (lysine, cystine, ornithine) in blood and urine. Hyperammonemia.
Gene	ARG1
Gene location	6p23
DNA testing available	On a research basis only
DNA testing detail	No common mutations known
Prenatal testing	Difficult due to lack of enzyme expression in fibroblasts. Direct fetal blood sampling is a possibility. Prenatal testing by direct DNA testing is not possible due to lack of common mutation. May be possible by RFLPs.
MS/MS Profile	Arginine and citrulline elevated. Arg - 152-1756uM
OMIM Link	http://www.ncbi.nlm.nih.gov/entrez/dispomim.cgi?id=207800
Genetests Link	http://genetests.org
Support Group	National Urea Cycle Disorders Foundation http://www.nucdf.org/ National Coalition for PKU and Allied Disorders http://www.pku-allieddisorders.org/ Children Living with Inherited Metabolic Diseases http://www.climb.org.uk/

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Health Resources and Service Administration, Genetic Services Branch,
MCH Project #:1H46 MC 00189-03 http://mchb.hrsa.gov

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Last updated:01/29/2007