[Importance of early diagnosis and treatment in the prognosis of type I Glutaric Acidaemia].
BACKGROUND
Glutaric Acidaemia type I (GA-I) is an autosomal recessive progressive neurodegenerative inborn error of metabolism caused by deficient activity of the enzyme glutaryl-CoA dehydrogenase (GCDH). In most cases, the diagnosis is established biochemically by the detection of glutaric acid and 3-hydroxy glutaric acid in urine and glutarylcarnitine in plasma. Patients excreting small amounts of glutaric acid may be overlooked.


OBJECTIVE
To investigate the value of expanded newborn screening by adding the measurement of urine glutarylcarnitine to conventional chromatography-mass spectrometry (GC-MS) in the diagnosis of GA-1.


METHODS
We report clinical and biochemical data in 5 GA-I patients diagnosed in our Hospital. Details regarding biochemical diagnosis are emphasised and the absence or presence of symptoms was correlated with neuroimaging findings, age at diagnosis and treatment.


RESULTS
Two patients showed high glutarylcarnitine levels in plasma and were identified by routine newborn GC-MS screening. Following early appropriate treatment they are asymptomatic 6 years later. Two patients with delayed diagnosis displayed neurological sequels in spite of treatment. The remaining patient, who presented with encephalopathic episode at age 8 months showed normal glutarylcarnitine levels in routine plasma GC-MS but high urine glutarylcarnitine levels in a retrospectively screened urine sample from the newborn period.


CONCLUSIONS
Early treatment seems to positively influence the clinical evolution of GA-I patients. Thus, improving the identification of GA-I represents an important diagnostic challenge. The urinary excretion of glutarylcarnitine is a specific biochemical marker of GA-I and allows the identification of patients without glutaric aciduria and with normal plasma acylcarnitine profiles.
Couce Pico
M L
ML
Unidad de Trastornos Metabólicos, Hospital Clínico Universitario, Santiago de Compostela, España. maria.luz.couce.pico@sergas.es
Castiñeiras Ramos
D E
DE
López Sousa
M
M
Fernández Seara
M J
MJ
Eirís Puñal
J
J
Cocho de Juan
J A
JA
D000592:Amino Acid Metabolism, Inborn Errors / Q000175:diagnosis* / Q000628:therapy*; D042241:Early Diagnosis; D005260:Female; D005977:Glutarates / Q000097:blood*; D006801:Humans; D007231:Infant, Newborn; D008297:Male; D011379:Prognosis
D005977:Glutarates; C035736:glutaric acid