Prediction of long-term outcome in glycine encephalopathy: a clinical survey

J Inherit Metab Dis. 2012 Mar;35(2):253-61. doi: 10.1007/s10545-011-9398-1. Epub 2011 Oct 15.


Objective: Glycine encephalopathy (GE) is a rare autosomal recessive inborn error of glycine degradation resulting in severe encephalopathy with ensuing poor outcome. Attenuated variants with a significantly better outcome have been reported. Early prediction of long-term outcome is not yet possible.

Methods: We compared the clinical and biochemical features of 45 children, each with a different course of the disease, to help determine predictors of long-term outcome.

Results: The most common presenting symptoms were hypotonia, seizures, and coma. In this study, 85% of the patients presented within the first week of life, and 15% presented after the neonatal period up to the age of 12 months. Developmental progress was made by 19% of those children presenting during the neonatal period and by 50% of those presenting in infancy. Initial CSF and plasma glycine concentrations were not useful in differentiating severe and attenuated outcome. A severe outcome was significantly associated with early onset of spasticity, frequent hiccupping, EEG burst-suppression or hypsarrhythmia patterns, microcephaly, and congenital or cerebral malformations, e.g. corpus callosum hypoplasia. An attenuated outcome was significantly associated with hyperactivity and choreiform movement disorders. We describe a severity score which facilitates the prediction of the outcome in patients with GE.

Conclusion: Prediction of the outcome of GE may be facilitated by recognizing selected clinical parameters and early neuroimaging findings.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • Child
  • Child, Preschool
  • Female
  • Humans
  • Hyperglycinemia, Nonketotic / diagnosis*
  • Hyperglycinemia, Nonketotic / pathology
  • Hyperglycinemia, Nonketotic / therapy*
  • Infant
  • Male
  • Pregnancy
  • Pregnancy Complications / diagnosis
  • Prenatal Diagnosis / methods
  • Prognosis
  • Time
  • Young Adult