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The urea cycle in the Rett syndrome
S Thomas1, V Oberholzer, J Wilson
1Department of Clinical Biochemistry, Institute of Child Health, London, England.
Brain & Development
|January 1, 1990
Summary
Rett syndrome (RS) girls showed normal urea cycle function and no hyperammonaemia after an alanine load. Some RS patients and mothers exhibited increased orotate excretion, similar to carriers of ornithine carbamoyltransferase (OCT) deficiency.
Area of Science:
- Biochemistry
- Genetics
- Neurodevelopmental Disorders
Background:
- Rett syndrome (RS) is a complex neurodevelopmental disorder.
- The urea cycle's in vivo functioning in RS has not been fully elucidated.
- Investigating metabolic pathways can offer insights into RS pathophysiology.
Purpose of the Study:
- To investigate the in vivo functioning of the urea cycle in girls with Rett syndrome.
- To compare urea cycle function in RS patients with healthy individuals and carriers of ornithine carbamoyltransferase (OCT) deficiency.
- To explore potential links between RS, urea cycle metabolites, and genetic factors.
Main Methods:
- Alanine load test administered to girls with RS and their mothers.
- Comparison of results with normal females, males, and obligate carriers of OCT deficiency.
- Analysis of post-load hyperammonaemia and urinary orotate excretion.
Main Results:
- No post-load hyperammonaemia was observed in non-medicated RS girls.
- Increased urinary orotate excretion was detected in some RS girls and their mothers.
- The pattern of orotate excretion in RS patients mirrored that of female carriers of OCT deficiency.
Conclusions:
- The urea cycle appears to function adequately in vivo in Rett syndrome.
- Elevated orotate excretion suggests a potential link to ornithine carbamoyltransferase (OCT) deficiency or a related X-linked mitochondrial protein abnormality.
- This finding may have implications for understanding mitochondrial dysfunction in the developing brain in RS.