[Cerebral creatine deficiency: first Spanish patients harbouring mutations in GAMT gene].
OBJECTIVE
Brain creatine (Cr) deficiencies are a group of inborn errors of metabolism that are characterized by an absence or severe reduction of brain Cr. Clinically, these patients can display psychomotor/mental retardation and language disorders, commonly associated with epilepsy or movement disorders. Three metabolic defects are known: two affect synthesis - guanidinoacetate metiltransferase (GAMT) and glycine amidinotransferase (AGAT) deficiencies- and one affect the Cr transporter (CRTR). We present the first three Spanish patients with GAMT deficiency, and we compare their clinical phenotype and treatment response with other published cases.


METHODS
The three patients presented mental retardation, epilepsy and autistic behaviour. Patient 1 also had severe chorea. Diagnosis was done by biochemical and genetic procedures (guanidinoacetate quantification, determination of GAMT activity and mutation analysis in the GAMT gene).


RESULTS
An increase of guanidinoacetate was detected in urine and plasma. Brain magnetic resonance spectroscopy revealed low Cr levels. Enzymatic studies revealed a decreased GAMT activity in fibroblasts. Molecular analysis detected pathogenic mutations in the GAMT gene. After the deficiency was confirmed, the patients started treatment with Cr. In addition, patient 2 and 3 received an arginine-restricted diet and ornithine supplements. All them showed a partial improvement.


CONCLUSIONS
Patients with GAMT deficiency have an unspecific but relatively constant clinical presentation. Brain Cr deficiency should be considered in patients with mental retardation of unknown aetiology, specially in those with movement disorders or epilepsy. Early diagnosis is important in cases with known treatment such as GAMT deficiency.
Sempere
Angela
A
Neuropediatría, Hospital Sant Joan de Déu y Centro de Investigación Biomédica en Red de Enfermedades Raras, ISCIII, Esplugues de Llobregat, Barcelona, España.
Fons
Carmen
C
Arias
Angela
A
Rodríguez-Pombo
Pilar
P
Merinero
Begoña
B
Alcaide
Patricia
P
Capdevila
Antoni
A
Ribes
Antonia
A
Duque
Rosario
R
Eirís
Jesús
J
Poo
Pilar
P
Fernández-Alvarez
Emilio
E
Campistol
Jaume
J
Artuch
Rafael
R
D000293:Adolescent; D001928:Brain Diseases, Metabolic / Q000175:diagnosis / Q000188:drug therapy / Q000235:genetics*; D002648:Child; D003401:Creatine / Q000172:deficiency*; D005260:Female; D050937:Guanidinoacetate N-Methyltransferase / Q000235:genetics*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009154:Mutation; D013030:Spain
C494506:GAMT protein, human; D050937:Guanidinoacetate N-Methyltransferase; D003401:Creatine