Glycine encephalopathy

Glycine encephalopathy is an inherent mistake of glycine metabolism in which big quantities of glycine accumulate in all body tissues, with the brain. A neonatal (classic) form and several atypical forms exist. The vast majority of individuals with NKH have the neonatal (classic) form; minorities of individuals with NKH have atypical forms. The neonatal type manifests in the primary hours to days of life with progressive lethargy, hypotonia, and myoclonic jerks leading to apnea and often death.

Surviving child’s developing deep mental retardation and obstinate seizures. The atypical forms variety from infantile- to late-onset milder disease to late-onset disease with a fast and severe course. The infantile type is characterized by onset of seizures beyond the neonatal period. About 80 percent of cases of glycine encephalopathy effect from mutations in the GLDC gene, while AMT mutations cause 10 percent to 15 percent of all cases. There are several forms of glycine encephalopathy. In the classic or neonatal form, symptoms usually develop as neurological symptoms in the first few days of life.

It characteristically presents with hypotonia, lethargy, apnea, and seizures and generally results in death by 1 year of age. Children with this situation develop normally until they are about 6 months old, when they experience delayed development and may begin having seizures. As they get older, many develop mental retardation, abnormal movements, and behavioral problems. Other atypical types of glycine encephalopathy appear later in childhood or adulthood and cause a variety of medical problems that primarily affect the nervous system. Rarely, the characteristic features of classical glycine encephalopathy improve with time.

These cases are classified as transient glycine encephalopathy. In this type of the condition, glycine levels reduce to normal or near-normal after being very high at birth. Many children with provisionally high glycine levels go on to extend normally and experience few long-term medical problems. Mental retardation and seizures occur in some affected individuals, however, even after glycine levels decrease.