Hyperprolinemia Type I

Hyperprolinemia Type I

National Organization for Rare Disorders, Inc.

Important

It is possible that the main title of the report Hyperprolinemia Type I is not the name you expected. Please check the synonyms listing to find the alternate name(s) and disorder subdivision(s) covered by this report.

Synonyms

  • Proline Oxidase Deficiency

Disorder Subdivisions

  • None

General Discussion

Two types of hyperprolinemia are recognized by physicians and clinical researchers. Each represents an inherited inborn error of metabolism involving the amino acid, proline. Proline is abundant in nature and readily found in a variety of foods.



Hyperprolinemia Type I (HP-I) is characterized by abnormally high levels of proline in the blood. The high level of blood proline is the result of a deficiency of the enzyme proline oxidase, which is essential to the normal breakdown (metabolism) of proline. There are often no clinical manifestations of HP-1.



Hyperprolinemia II (HP-II) results from the deficiency of another enzyme and also results in high blood proline levels, as well as other more severe clinical manifestations than are seen in HP-I. Mild mental retardation and convulsions are commonly associated with HP-II.

Symptoms

Hyperprolinemia Type I is the result of proline oxidase deficiency and is characterized by an abnormally high proline blood level. Levels of the amino acids hydroxyproline and glycine in the blood are also higher than normal. Some clinicians believe that kidney abnormalities may be associated with HP-I, although this is disputed. The signs and symptoms of HP-I, other than the high levels of amino acids in the blood and urine, are vague. Often, this disorder is described as benign.

Causes

Hyperprolinemia Type I is an autosomal recessive disorder. The gene involved is located on the long arm of chromosome 22. Chromosomes, which are present in the nucleus of human cells, carry the genetic characteristics of each individual. Pairs of human chromosomes are numbered from 1 through 22, with an unequal 23rd pair of X and Y chromosomes for males, and two X chromosomes for females. Each chromosome has a short arm designated as "p" and a long arm identified by the letter "q". Chromosomes are further subdivided into many bands that are numbered. For example, chromosome 22q11.2 refers to band 11 on the long arm of chromosome 22.



Recessive genetic disorders occur when an individual inherits the same abnormal gene for the same trait from each parent. If an individual receives one normal gene and one gene for the disease, the person will be a carrier for the disease, but usually will not show symptoms. The risk for two carrier parents to both pass the defective gene and, therefore, have an affected child is 25% with each pregnancy. The risk to have a child who is a carrier like the parents is 50% with each pregnancy. The chance for a child to receive normal genes from both parents and be genetically normal for that particular trait is 25%. The risk is the same for males and females.



All individuals carry a few abnormal genes. Parents who are close relatives (consanguineous) have a higher chance than unrelated parents to both carry the same abnormal gene, which increases the risk to have children with a recessive genetic disorder.

Affected Populations

Hyperprolinemia Type I is a very rare disorder that is present at birth. It affects males and females in equal numbers.

Standard Therapies

Diagnosis

HP-I is recognized by elevated blood proline levels. (The normal level is approximately 450 units, but people with HP-1 may have levels of 1900 to 2000 units.) Often, the diagnosis is made by exclusion. After failure to arrive at a diagnosis by other means, a blood proline level is ordered. The result confirms the diagnosis.



Treatment.

Because proline is so widespread among foods, attempts to control blood proline levels by restrictive dieting have not succeeded. Because the medical consequences of this particular inborn error of metabolism appear to be modest or inconsequential, many physicians do not take an aggressive approach toward treatment.

Investigational Therapies

Information on current clinical trials is posted on the Internet at www.clinicaltrials.gov. All studies receiving U.S. government funding, and some supported by private industry, are posted on this government web site.



For information about clinical trials being conducted at the NIH Clinical Center in Bethesda, MD, contact the NIH Patient Recruitment Office:



Tollfree: (800) 411-1222

TTY: (866) 411-1010

Email: prpl@cc.nih.gov



For information about clinical trials sponsored by private sources, contact:

www.centerwatch.com

References

TEXTBOOKS

Phang JM, Yeh GC, Scriver CR. In: Scriver CR, Beaudet AL, Sly WS, et al. Eds. The Metabolic Molecular Basis of Inherited Disease. 7th ed. McGraw-Hill Companies. New York, NY; 1995:1125-26; 1343-44.



JOURNAL ARTICLES

Jacquet H, Raux G, Thibaut F, et al. PRODH mutations and hyperprolinemia ina subset of schizophrenic patients. Hum Mol Genet. 2002;11:2243-49.



Humberclaude V, Rivier F, Roubertie A, et al. Is hyperprolinemia type I actually a benign trait? Report of a case with severe neurologic involvement and vigabatrin intolerance. J Child Neurol. 2001;16:622-23.



Goodman BK, Rutberg J, Lin WW, et al. Hyperprolinemia in patients with deletion (22)(q11.2) syndrome. J Inherit Metab Dis. 2000;23:847-48.



Shivananda, Christopher R, Kumar P. Type I hyperprolinemia. Indian J Pediatr. 2000;67:541-43.



Oyanagi K, Tsuchiyama A, Itakura Y, et al. Clinical, biochemical and enzymatic studies in type I hyperprolinemia associated with chromosomal activity. Tohoku J Exp Med. 1987;151:465-75.



FROM THE INTERNET

McKusick VA, Ed. Online Mendelian Inheritance in Man (OMIM). The Johns Hopkins University. Entry Number; 239500: Last Edit Date; 9/10/2002.

Resources

CLIMB (Children Living with Inherited Metabolic Diseases)

Climb Building

176 Nantwich Road

Crewe, CW2 6BG

United Kingdom

Tel: 4408452412173

Fax: 4408452412174

Email: enquiries@climb.org.uk

Internet: http://www.CLIMB.org.uk



NIH/National Institute of Diabetes, Digestive & Kidney Diseases

Office of Communications & Public Liaison

Bldg 31, Rm 9A06

31 Center Drive, MSC 2560

Bethesda, MD 20892-2560

Tel: (301)496-3583

Email: NDDIC@info.niddk.nih.gov

Internet: http://www2.niddk.nih.gov/



Genetic and Rare Diseases (GARD) Information Center

PO Box 8126

Gaithersburg, MD 20898-8126

Tel: (301)251-4925

Fax: (301)251-4911

Tel: (888)205-2311

TDD: (888)205-3223

Internet: http://rarediseases.info.nih.gov/GARD/



For a Complete Report

This is an abstract of a report from the National Organization for Rare Disorders, Inc.® (NORD). Cigna members can access the complete report by logging into myCigna.com. For non-Cigna members, a copy of the complete report can be obtained for a small fee by visiting the NORD website. The complete report contains additional information including symptoms, causes, affected population, related disorders, standard and investigational treatments (if available), and references from medical literature. For a full-text version of this topic, see http://www.rarediseases.org/search/rdblist.html.

This information does not replace the advice of a doctor. Healthwise, Incorporated disclaims any warranty or liability for your use of this information. Your use of this information means that you agree to the Terms of Use . How this information was developed to help you make better health decisions.

Healthwise, Healthwise for every health decision, and the Healthwise logo are trademarks of Healthwise, Incorporated.