Carbamoyl Phosphate Synthetase I Deficiency, Hyperammonemia due to

Alternative Names

  • Carbamoyl Phosphate Synthetase I Deficiency
  • CPS I Deficiency
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WHO-ICD-10 version:2010

Endocrine, nutritional and metabolic diseases

Metabolic disorders

OMIM Number


Mode of Inheritance

Autosomal recessive

Gene Map Locus



Carbamoyl Phosphate Synthetase I Deficiency (CPSID) is a rare autosomal recessive disorder that is strictly limited to the liver and intestine, and results in congenital hyperammonemia and defective citrulline synthesis. The management of CPSID may include a strict lifelong diet of very limited protein intake, citrulline and arginine supplementation, and administration of both sodium benzoate and sodium phenylbutyrate.

Epidemiology in the Arab World

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Subject IDCountrySexFamily HistoryParental ConsanguinityHPO TermsVariantZygosityMode of InheritanceReferenceRemarks
237300.1.1LebanonMaleYesYes Hyperammonemia; Encephalopathy; Respir...NM_001875.4:c.3558+1G>C, NM_001875.4:c.4101+2T>CHeterozygousAutosomal, RecessiveKlaus et al, 2009
237300.1.2LebanonMaleYes Hyperammonemia; Confusion; Adult onset;NM_001875.4:c.3558+1G>C, NM_001875.4:c.4101+2T>CHeterozygousAutosomal, RecessiveKlaus et al, 2009 Grandfather of 23730...
237300.2United Arab EmiratesUnknown Hyperammonemia; Neonatal;NM_001875.4:c.1590dupHomozygousAutosomal, RecessiveAl-Shamsi et al. 2014
237300.3OmanUnknownNM_001875.4:c.1590dupHomozygousAutosomal, RecessiveBen-Rebeh et al. 2012

Other Reports


Granot et al. (1986) reported an Arab child in whom the diagnosis of partial CPS deficiency was first made when she presented at nine years of age with hyperammonemic coma simulating Reye syndrome. Despite intensive therapy directed toward lowering of ammonia levels, she sustained irreversible brain damage. 

United Arab Emirates

Al-Shamsi et al. (2014) calculated the birth prevalence of CPSID  at less than 0.98 per 100,000 live births.

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