Arginemia

(Redirected from Arginase deficiency)
Jump to: navigation, search
Arginemia
L-arginine-skeletal-(tall).png
Arginine
OMIM 207800
DiseasesDB 29677
eMedicine ped/132 
MeSH D020162

WikiDoc Resources for Arginemia

Articles

Most recent articles on Arginemia

Most cited articles on Arginemia

Review articles on Arginemia

Articles on Arginemia in N Eng J Med, Lancet, BMJ

Media

Powerpoint slides on Arginemia

Images of Arginemia

Photos of Arginemia

Podcasts & MP3s on Arginemia

Videos on Arginemia

Evidence Based Medicine

Cochrane Collaboration on Arginemia

Bandolier on Arginemia

TRIP on Arginemia

Clinical Trials

Ongoing Trials on Arginemia at Clinical Trials.gov

Trial results on Arginemia

Clinical Trials on Arginemia at Google

Guidelines / Policies / Govt

US National Guidelines Clearinghouse on Arginemia

NICE Guidance on Arginemia

NHS PRODIGY Guidance

FDA on Arginemia

CDC on Arginemia

Books

Books on Arginemia

News

Arginemia in the news

Be alerted to news on Arginemia

News trends on Arginemia

Commentary

Blogs on Arginemia

Definitions

Definitions of Arginemia

Patient Resources / Community

Patient resources on Arginemia

Discussion groups on Arginemia

Patient Handouts on Arginemia

Directions to Hospitals Treating Arginemia

Risk calculators and risk factors for Arginemia

Healthcare Provider Resources

Symptoms of Arginemia

Causes & Risk Factors for Arginemia

Diagnostic studies for Arginemia

Treatment of Arginemia

Continuing Medical Education (CME)

CME Programs on Arginemia

International

Arginemia en Espanol

Arginemia en Francais

Business

Arginemia in the Marketplace

Patents on Arginemia

Experimental / Informatics

List of terms related to Arginemia


Arginemia (also called arginase deficiency) is a congenital disorder where arginase deficiency causes a high level of arginine and ammonia in the blood. Ammonia, which is formed when proteins are broken down in the body, is toxic if levels become too high. The nervous system is especially sensitive to the effects of excess ammonia.

Arginase deficiency usually becomes evident by about the age of 3. It most often appears as stiffness, especially in the legs, caused by abnormal tensing of the muscles (spasticity). Other symptoms may include slower than normal growth, developmental delay and eventual loss of developmental milestones, mental retardation, seizures, tremor, and difficulty with balance and coordination (ataxia). Occasionally, high protein meals or stress caused by illness or periods without food (fasting) may cause ammonia to accumulate more quickly in the blood. This rapid increase in ammonia may lead to episodes of irritability, refusal to eat, and vomiting.

In some affected individuals, signs and symptoms of arginase deficiency may be less severe, and may not appear until later in life.

Mutations in the ARG1 gene cause arginase deficiency. Arginase deficiency belongs to a class of genetic diseases called urea cycle disorders. The urea cycle is a sequence of reactions that occurs in liver cells. This cycle processes excess nitrogen, generated when protein is used by the body, to make a compound called urea that is excreted by the kidneys.

The ARG1 gene provides instructions for making an enzyme called arginase. This enzyme controls the final step of the urea cycle, which produces urea by removing nitrogen from arginine. In people with arginase deficiency, arginase is damaged or missing, and arginine is not broken down properly. As a result, urea cannot be produced normally, and excess nitrogen accumulates in the blood in the form of ammonia. The accumulation of ammonia and arginine are believed to cause the neurological problems and other signs and symptoms of arginase deficiency.

Arginase deficiency is inherited in an autosomal recessive pattern.

This condition is inherited in an autosomal recessive pattern, which means two copies of the gene in each cell are altered. Most often, the parents of an individual with an autosomal recessive disorder are carriers of one copy of the altered gene but do not show signs and symptoms of the disorder.

Differential diagnosis

Arginase deficiency must be differentiated from other diseases that cause neurological manifestations in infants.

Diseases Type of motor abnormality Clinical findings Laboratory findings and diagnostic tests Radiographic findings
Spasticity Hypotonia Ataxia Dystonia
Leigh syndrome - - + +
Niemann-Pick disease type C - - + +
  • Abnormal liver function tests
  • Fibroblast cell culture with filipin staining
Infantile Refsum disease - + + - Elevated plasma VLCFA levels --
Adrenoleukodystrophy + - - -
  • Elevated plasma VLCFA levels
  • Molecular genetic testing for mutations in the ABCD1 gene
--
Zellweger syndrome - + - - --
Pyruvate dehydrogenase deficiency + + + -
  • Elevated lactate and pyruvate levels in blood and CSF
  • Abnormal PDH enzymatic activity in cultured fibroblasts
--
Arginase deficiency + - - - --
Holocarboxylase synthetase deficiency - + - - Elevated levels of:
  • Beta-hydroxyisovalerate
  • Beta-methylcrotonylglycine
  • Beta-hydroxypropionate
  • Methylcitrate
  • Tiglylglycine
--
Glutaric aciduria type 1 - - - + Elevated levels of:
Ataxia telangiectasia - - + - --
Pontocerebellar hypoplasias - + - - Genetic testing for PCH gene mutations
Metachromatic leukodystrophy - + + -
  • Deficient arylsulfatase A enzyme activity in leukocytes or cultured skin fibroblasts
--
Pelizaeus-Merzbacher + - + -
Angelman syndrome - - + -
  • Methylation studies and chromosome microarray to detect chromosome 15 anomalies and UBE3A mutations
--
Rett syndrome + - - +
  • Occurs almost exclusively in females
  • Normal development during first six months followed by regression and loss of milestones
  • Loss of speech capability
  • Stereotypic hand movements
  • Seizures
  • Autistic features
  • Clinical diagnosis
  • Genetic testing for MECP2 mutations
--
Lesch-Nyhan syndrome + - - + --
Miller-Dieker lissencephaly + + - -
  • Cytogenetic testing for 17p13.3 microdeletion
--
Dopa-responsive dystonia + - - +
  • Onset in early childhood
  • Symptoms worsen with fatigue and exercise
  • Positive response to a trial of levodopa
--


References



Linked-in.jpg