Nonketotic Hyperglycinemi

Genetic Type: autosomal recessive

Prevalence : approximately 1:12,000 northern Finland , Taiwan, there are a few cases , prevalence is unknown.

Etiology: the liver , kidneys, and brain glycine cleavage system (glycine cleavage system, GCS) is one of the four proteins caused by defects in the metabolic abnormalities : P protein (a pyridoxal phosphate-dependant glycine decarboxylase), H protein ( a lipoic acid-containing protein), T protein (a tetrahydrofolate-requiring enzyme), and L- protein (lipoamide dehydrogenase), most patients have defects in the P protein , a small part of the T protein defect . High glycine on the developing brain damage.


Symptoms:

A neonatal onset : birth, normal, low tension occurs , reflex response is low, epilepsy, cramps, suffocation , drowsiness, muscle stiffness , or coma and other neurological symptoms less than 48 hours and the rapid deterioration in the majority of cases within a few weeks death , the survivors will have severe developmental delays may occur with myoclonic epilepsy Tai episodes of epilepsy, high glycine hyperlipidemia. Hiccup

Second, the hair: onset in infancy , with moderate mental retardation .

Third, late onset : neonatal period without exception, in the infant or adolescent onset.



Diagnostic tests :

First, the analysis of amino acids in the blood : an abnormal rise in blood glycine .

Second, the gas layer phase analyzer checks the urine organic acids : None keto acid .

※ compare cerebrospinal fluid and plasma concentrations of glycine , the ratio is as follows:

1 of cerebrospinal fluid glycine : The plasma glycine > 0.06 = non- ketone high glycine hyperlipidemia

(2) of the cerebrospinal fluid glycine : glycine plasma of < 0.02 and > 0.04 = Normal

3 cerebrospinal fluid glycine : plasma glycine < 0.02 = ketone high acid blood.

4 Non- keto high glycine hyperlipidemia measured brain activity does not fall glycine ; ketone high glycine hyperlipidemia brain activity of glycine is showing normal .

Three , hepatocellular enzyme activity analysis : glycine activity of liver cells are no or very low , in the late -onset can only be measured by residual activity .

Fourth, gene mutation analysis



Prenatal diagnosis:

Placental villus sampling : development of analytical villi glycine decomposition system enzyme activity , there are false negatives , need to merge and mutation analysis .

Amniotic fluid cells without glycine cleavage system enzyme activity, it does not apply to prenatal genetic diagnosis.


Treatment:

Reduce glycine concentration method :

1 diet: no glycine and its precursors serine (serine) or restricted protein diet.

2 Drugs:

● benzoate (Benzoate) combined with glycine as hippuric acid and excreted by the kidneys .

● injection ursodeoxychoic acid glycine to bind bile excretion.

● Use tranquilizers ( such as Valium), methionine (methionine), antidote (Leucovorin), or choleretic agent (Choline) and other drugs, improve symptoms.

● glycine is nerve agents hypothesis of the use of NMDA antagonists ( eg Ketamine Ketamine ) or antitussive (dextromethorphan) ( eg

Dextromethorphan). Part of the neurological symptoms and improve brain waves .

● High doses of sodium benzoate (sodium benzoate) A case HKH treatment .