- Glycine synthase deficiency
- Hyperglycinemia nonketotic
- Nonketotic hyperglycinemia
Your QuestionIs it necessary to restrict protein intake in children that have this disorder? If so, what are the risks if protein intake is not restricted?
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The goal of treatment is to reduce the amount of glycine in the plasma (blood). Treatment may involve a medication called sodium benzoate, which binds with glycine allowing it to be passed out in the urine, and dextromethorphan, ketamine, or felbamate, which block some of the harmful effects of excessive glycine. These treatments may help control seizures, increase alertness, and in mildly affected individuals, improve behavior. Drug dosage must be individually tailored and requires regular and careful monitoring. Studies regarding the effectiveness of these treatments are ongoing. Mildly affected individuals may receive the greatest benefit from treatment, particularly if treatment is started early.
Other treatments include drugs to control seizures (anti-epileptic drugs); assistive devices or surgeries to aid with feeding and swallowing (e.g., gastrostomy tube); physical therapy; and scoliosis management. Parents and family members may benefit from genetic counseling. Click here to learn more about genetic consultations.
For further details on treatment, please visit the following link to GeneReviews. GeneReviews provides current, expert-authored, peer-reviewed, full-text articles describing the application of genetic testing to the diagnosis, management, and genetic counseling of patients with specific inherited conditions. Because of the complexity of the information in the article, we recommend that you review it with a health care provider.
The following online resources can help you find a genetics professional in your community:
- The National Society of Genetic Counselors provides a searchable directory of US and international genetic counseling services.
- The American College of Medical Genetics has a searchable database of US genetics clinics.
- The University of Kansas Medical Center provides a list of US and international genetic centers, clinics, and departments.
- The American Society of Human Genetics maintains a database of its members, which includes individuals who live outside of the United States. Visit the link to obtain a list of the geneticists in your country, some of whom may be researchers that do not provide medical care.
- Hamosh A, Scharer G, Van Hove J. Glycine encephalopathy. GeneReviews. November 2009; http://www.ncbi.nlm.nih.gov/books/NBK1357/. Accessed 11/10/2011.
- Van Hove JL, Vande Kerckhove K, Hennermann JB, Mahieu V, Declercq P, Mertens S, De Becker M, Kishnani PS, Jaeken J. Benzoate treatment and the glycine index in nonketotic hyperglycinaemia. J Inherit Metab Dis. 2005;28(5):651-63; http://www.ncbi.nlm.nih.gov/pubmed/16151895. Accessed 8/26/2011.