ContentsSynopsisCodesReferences
Potentially life-threatening emergency
Nonketotic hyperglycinemia
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Other Resources UpToDate PubMed
Potentially life-threatening emergency

Nonketotic hyperglycinemia

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Other Resources UpToDate PubMed

Synopsis

Nonketotic hyperglycinemia (NKH, glycine encephalopathy) is an inborn error of glycine metabolism impairing activity of the glycine cleavage system and causing glycine buildup throughout the body and brain tissue. An autosomal recessive inherited life-threatening disorder, elevated glycine is measured in blood and cerebrospinal fluid.

In the neonatal form, onset is within days of birth. Hallmarks include hiccups, lethargy, poor feeding, hypotonia, myoclonic jerks, and seizures. Progressively, breathing difficulties and coma lead to death, if untreated. Surviving infants may experience spasticity, intractable seizures, and profound developmental delay.

Other forms include the infantile form (starting around 6 months of age) and atypical glycine encephalopathy (age 2 to mid-30s) with symptoms ranging from mild to severe within a clinical spectrum.

There is no definitive cure for NKH. Management includes a ketogenic diet to restrict protein and reduce glycine burden. Medications can control seizures, including antiepileptic medications (valproate is contraindicated in patients with NKH).

For more information, see OMIM.

Codes

ICD10CM:
E72.51 – Non-ketotic hyperglycinemia

SNOMEDCT:
237939006 – Non-ketotic hyperglycinemia

References

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Last Updated: 03/29/2017
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Potentially life-threatening emergency
Nonketotic hyperglycinemia
Print 1 Images
Nonketotic hyperglycinemia : Seizures, Fatigue, Apnea, Hypotonia, Myoclonus, Developmental delay, Hiccups, Poor feeding
Copyright © 2018 VisualDx®. All rights reserved.