Carbamoyl Phosphate Synthetase Deficiency Follow-up

  • Author: Karl S Roth, MD; Chief Editor: Bruce Buehler, MD   more...
 
Updated: Mar 13, 2012
 

Further Outpatient Care

A biochemical geneticist or metabolic disease specialist should closely observe any patient with a diagnosed urea cycle defect, whether partial or complete. Oral sodium phenylbutyrate and arginine are often needed.

A trained nutritionist should scrupulously monitor the diet of a patient with carbamoyl phosphate synthetase (CPS) deficiency.

Periodic intellectual and neurologic evaluations are essential.

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Prognosis

A positive outcome is extremely unlikely in individuals with neonatal onset.

Usually, the best prognosis is an infant who will be seriously impaired and will develop recurrent hyperammonemic episodes throughout infancy and childhood, sustaining further insults to the CNS.

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Patient Education

As an autosomal recessive trait, each parent is assumed to be an obligate heterozygote for CPS I deficiency. The likelihood of a recurrence is 25% (1:4) with each subsequent pregnancy, regardless of fetal sex.

Prenatal diagnosis is theoretically available. If desired, contact the laboratory as early as possible.

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Contributor Information and Disclosures
Author

Karl S Roth, MD  Professor and Chair, Department of Pediatrics, Creighton University School of Medicine

Karl S Roth, MD is a member of the following medical societies: Alpha Omega Alpha, American Academy of Pediatrics, American College of Nutrition, American Pediatric Society, American Society for Clinical Nutrition, American Society of Nephrology, Association of American Medical Colleges, Medical Society of Virginia, New York Academy of Sciences, Sigma Xi, Society for Pediatric Research, and Southern Society for Pediatric Research

Disclosure: Nothing to disclose.

Specialty Editor Board

Robert D Steiner, MD  Credit Unions for Kids Professor of Pediatric Research, Professor of Pediatrics and Molecular and Medical Genetics, Vice Chair for Research, Department of Pediatrics, Faculty, Program in Molecular and Cellular Biosciences, Oregon Health and Science University School of Medicine; Attending Physician, Doernbecher Children's Hospital; Staff Consultant, Director of Metabolic Bone Disease Clinic, Shriners Hospital Portland

Robert D Steiner, MD is a member of the following medical societies: American Academy of Pediatrics, American Association for the Advancement of Science, American College of Medical Genetics, American Society of Human Genetics, Oregon Medical Association, Society for Inherited Metabolic Disorders, Society for Pediatric Research, Society for the Study of Inborn Errors of Metabolism, and Western Society for Pediatric Research

Disclosure: Amicus Honoraria Consulting; Actelion Honoraria Consulting; Actelion Honoraria Speaking and teaching; Biomarin Honoraria Consulting; Genzyme Honoraria Consulting; Shire Honoraria Consulting

Mary L Windle, PharmD  Adjunct Associate Professor, University of Nebraska Medical Center College of Pharmacy; Editor-in-Chief, Medscape Drug Reference

Disclosure: Nothing to disclose.

Leonard G Feld, MD, PhD, MMM, FAAP  Sara H Bissell and Howard C Bissell Endowed Chair in Pediatrics, Chief Medical Officer, Levine Children's Hospital, Carolinas Medical Center

Leonard G Feld, MD, PhD, MMM, FAAP is a member of the following medical societies: American Academy of Pediatrics, American College of Physician Executives, American Society of Nephrology, American Society of Pediatric Nephrology, International Society of Nephrology, and Juvenile Diabetes Foundation International

Disclosure: Nothing to disclose.

Paul D Petry, DO, FACOP, FAAP  Consulting Staff, Freeman Pediatric Care, Freeman Health System

Paul D Petry, DO, FACOP, FAAP is a member of the following medical societies: American Academy of Osteopathy, American Academy of Pediatrics, American College of Osteopathic Pediatricians, and American Osteopathic Association

Disclosure: Nothing to disclose.

Chief Editor

Bruce Buehler, MD  Professor, Department of Pediatrics and Genetics, Director RSA, University of Nebraska Medical Center

Bruce Buehler, MD is a member of the following medical societies: American Academy for Cerebral Palsy and Developmental Medicine, American Academy of Pediatrics, American Association on Mental Retardation, American College of Medical Genetics, American College of Physician Executives, American Medical Association, and Nebraska Medical Association

Disclosure: Nothing to disclose.

References

  1. Yefimenko I, Frequet V, Marco-Marin C, et al. Understanding carbomyl phosphate synthetase deficiency: impact of clinical mutations on enzyme functionality. J Mol Biol. 2005;349:127-141.

  2. Keskinen P, Siitonen A, Salo M. Hereditary urea cycle diseases in Finland. Acta Paediatr. Oct 2008;97(10):1412-9. [Medline].

  3. Funghini S, Thusberg J, Spada M, Gasperini S, Parini R, Ventura L, et al. Carbamoyl phosphate synthetase 1 deficiency in Italy: clinical and genetic findings in a heterogeneous cohort. Gene. Feb 10 2012;493(2):228-34. [Medline].

  4. Wong LJ, Craigen WJ, O'Brien WE. Postpartum coma and death due to carbamoyl-phosphate synthetase I deficiency. Ann Intern Med. Feb 1 1994;120(3):216-7. [Medline].

  5. Häberle J, Shchelochkov OA, Wang J, Katsonis P, Hall L, Reiss S, et al. Molecular defects in human carbamoy phosphate synthetase I: mutational spectrum, diagnostic and protein structure considerations. Hum Mutat. Jun 2011;32(6):579-89. [Medline].

  6. Batshaw ML, Brusilow S, Waber L, Blom W, et al. Treatment of inborn errors of urea synthesis: activation of alternative pathways of waste nitrogen synthesis and excretion. N Engl J Med. Jun 10 1982;306(23):1387-92. [Medline].

  7. Berry GT, Steiner RD. Long-term management of patients with urea cycle disorders. J Pediatr. Jan 2001;138(1 Suppl):S56-60; discussion S60-1. [Medline].

  8. Eather G, Coman D, Lander C, et al. Carbamyl phosphate synthase deficiency: diagnosed during pregnancy in a 41-year-old. J Clin Neurosci. 2006;13:702-6.

  9. Eeds AM, Hall LD, Yadav M, et al. The frequent observation of evidence for nonsense-mediated decay in RNA from patients with caramyl phosphate synthetase I deficiency. Mol Genet Metab. 2006;89:80-86.

  10. Farriaux JP, Ponte C, Pollitt RJ, Lequien P, et al. Carbamyl-phosphate-synthetase deficiency with neonatal onset of symptoms. Acta Paediatr Scand. Jul 1977;66(4):529-34. [Medline].

  11. Finckh U, Kohlschutter A, Schafer H, Sperhake K, et al. Prenatal diagnosis of carbamoyl phosphate synthetase I deficiency by identification of a missense mutation in CPS1. Hum Mutat. 1998;12(3):206-11. [Medline].

  12. Freeman JM, Nicholson JF, Schimke RT, Rowland LP, et al. Congenital hyperammonemia. Association with hyperglycinemia and decreased levels of carbamyl phosphate synthetase. Arch Neurol. Nov 1970;23(5):430-7. [Medline].

  13. Gropman AL, Summar M, Leonard JV. Neurological implications of urea cycle disorders. J Inherit Metab Dis. Nov 2007;30(6):865-79. [Medline].

  14. Kojic J, Robertson PL, Quint DJ. Brain glutamine by MRS in a patient with urea cycle disorder and coma. Pediatr Neurol. 2005;32:143-146.

  15. Steiner RD, Cederbaum SD. Laboratory evaluation of urea cycle disorders. J Pediatr. Jan 2001;138(1 Pt 2):S21-S29.

  16. Summar ML. Molecular genetic research into carbamoyl-phosphate synthase I: molecular defects and linkage markers. J Inherit Metab Dis. 1998;21 Suppl 1:30-9. [Medline].

  17. Summar ML, Hall L, Christman B. Environmentally determined genetic expression: clinical correlates with molecular variants of carbamyl phosphate synthetase I. Mol Genet Metab. 2004;81Supplement 1:S12-S19.

  18. Verbiest HB, Straver JS, Colombo JP, van der Vijver JC, et al. Carbamyl phosphate synthetase-1 deficiency discovered after valproic acid-induced coma. Acta Neurol Scand. Sep 1992;86(3):275-9. [Medline].

 
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Compounds comprising the urea cycle are numbered sequentially, beginning with carbamyl phosphate (1). At this step, the first waste nitrogen is incorporated into the cycle; at this step, N-acetylglutamate exerts its regulatory control on the mediating enzyme, carbamyl phosphate synthetase (CPS). 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.
 
 
 
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