Amino Acid Disorders

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Disease Name Argininemia/ arginase deficiency
Alternate name(s) Hyperargininemia ARG I Deficiency
Acronym ARG I
Disease Classification Amino Acid Disorder
Variants Yes
Variant nameARG II
Symptom onsetPrimarily 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
PopulationN/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 Enzymearginase
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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