<%server.execute "isdev.asp"%> Unusual phenotype of glucose transport protein type 1 deficiency syndrome: A case report and literature review Posar A, Santucci M - J Pediatr Neurosci
home : about us : ahead of print : current issue : archives search instructions : subscriptionLogin 
Users online: 305      Small font sizeDefault font sizeIncrease font size Print this page Email this page


 
  Table of Contents    
CASE REPORT
Year : 2014  |  Volume : 9  |  Issue : 1  |  Page : 36-38
 

Unusual phenotype of glucose transport protein type 1 deficiency syndrome: A case report and literature review


Department of Biomedical and Neuromotor Sciences, Child Neurology and Psychiatry Unit, IRCCS Institute of Neurological Sciences of Bologna, University of Bologna, Bologna, Italy

Date of Web Publication25-Apr-2014

Correspondence Address:
Annio Posar
Department of Biomedical and Neuromotor Sciences, Child Neurology and Psychiatry Unit, IRCCS Institute of Neurological Sciences of Bologna, University of Bologna, Via Altura 3, Bologna - 40139
Italy
Login to access the Email id

Source of Support: None, Conflict of Interest: None


DOI: 10.4103/1817-1745.131481

Rights and Permissions

 

   Abstract 

The glucose transport protein type 1 (GLUT1) deficit causes a chronic brain energy failure. The classic phenotype of GLUT1 deficiency syndrome is characterized by: Mild to severe motor delay and mental retardation; infantile-onset epilepsy; head growth deceleration; movement disorders (ataxia, dystonia, spasticity); and non-epileptic paroxysmal events (intermittent ataxia, periodic confusion, recurrent headaches). During last years the classic phenotype of this syndrome, as originally reported, has expanded. We report the atypical phenotype of a boy with GLUT1 deficiency syndrome, characterized by mild mental retardation and drug-resistant absence seizures with onset at the age of 6 years, without movement disorders nor decrease of head circumference. A prompt diagnosis of this disorder is mandatory since the ketogenic diet might represent an effective treatment.


Keywords: EEG, epilepsy, Glucose transport protein type 1 deficiency syndrome, ketogenic diet, mental retardation


How to cite this article:
Posar A, Santucci M. Unusual phenotype of glucose transport protein type 1 deficiency syndrome: A case report and literature review. J Pediatr Neurosci 2014;9:36-8

How to cite this URL:
Posar A, Santucci M. Unusual phenotype of glucose transport protein type 1 deficiency syndrome: A case report and literature review. J Pediatr Neurosci [serial online] 2014 [cited 2017 Jul 24];9:36-8. Available from: http://www.pediatricneurosciences.com/text.asp?2014/9/1/36/131481



   Introduction Top


Glucose transport protein type 1 (GLUT1) delivers glucose to the brain from bloodstream and is therefore crucial for an adequate energy provision. [1],[2],[3],[4],[5],[6] GLUT1 deficiency syndrome, inducing a chronic brain energy failure, is caused by mutations of the solute carrier family 2 (facilitated glucose transporter) member 1 (SLC2A1) gene, located on the chromosome 1p34.2. Most mutations are de novo; inheritance in familial cases is mostly autosomal dominant. [2],[3],[4],[5],[6]

The classic phenotype of GLUT1 deficiency syndrome is characterized by: Mild to severe motor delay and mental retardation; infantile-onset epilepsy; head growth deceleration, possibly resulting in acquired microcephaly; movement disorders (ataxia, dystonia, spasticity); and non-epileptic paroxysmal events (intermittent ataxia, periodic confusion, recurrent headaches). [1],[2] Reported features of epilepsy in this condition are heterogeneous; generalized tonic-clonic and absence seizures prevail. [7] Lumbar puncture shows hypoglycorrhachia, with a reduced cerebrospinal fluid/blood glucose ratio in most patients. The ketogenic diet has proved to markedly improve epilepsy, movement disorders and head growth, while the cognitive effects are less pronounced. [1],[2],[3],[4],[5],[6]

We describe the atypical phenotype of a boy with GLUT1 deficiency syndrome.


   Case Report Top


The patient's family history was positive for: A not better specified psychiatric disorder and somnambulism in the mother; epilepsy and mental retardation, in a paternal uncle and a paternal cousin, respectively. The mother had some spontaneous abortions. He was an only child, born at the 36 th week of gestation by Caesarean section due to hypertensive gestosis, after a two-placenta twin pregnancy, with the intrauterine death of the other fetus. Apgar Index was 7 (1') and 8 (5'); birth weight was 3040 grams. Cyanosis and jaundice at the birth were reported; jaundice was treated by phototherapy and exsanguinotransfusion. He had a bilateral nuclear congenital cataract. Height and weight growth were normal. There was a mild, global delay of psychomotor development. At the age of 4 years 1 month, EEG tracing during wakefulness, performed due to the psychomotor retardation, was normal. From the age of about 4 years he has suffered from headache several times monthly, sometimes associated with nausea and vomiting, treated with paracetamol. At the age of about 6 years, he started to present, especially in the morning, short but frequent (even several times a day) episodes of loss of consciousness, eye closure, inconstant eyelid myoclonia. The events could occur isolated or close together resulting in falling asleep but showing amelioration on awakening. The drowsiness associated with the long clusters of these events was a major problem in his everyday life, especially at school. When he came to our observation, he was 9 years 8 months old. Neurological examination showed only a mild, aspecific incoordination; head circumference corresponded to the fiftieth percentile. He often appeared tired, sleepy, and lazy. Neuropsychological evaluation showed a mild mental retardation (Wechsler Scale), stable during the follow-up, with a significant prevalence of verbal intelligence quotient (IQ) versus performance IQ; an aspecific learning disorder was evident. EEG revealed diffuse paroxysmal abnormalities and several brief absence seizures have been recorded [Figure 1] and [Figure 2]. Electromyography as well as motor and sensory nerve conduction study was normal. Brain MRI was normal. High-resolution kariotype and search for fragile X syndrome were normal, as well as a metabolic screening including creatine kinase, lactic acid at baseline and after exercise, thyroid hormones, tests for celiac disease, ammonia, serum and urinary aminoacids, and urinary oligosaccharides. Absence seizures were drug resistant to ethosuximide, levetiracetam, lamotrigine, and valproate, with only transient improvements after beginning a drug. After antiepileptic therapy start, we found episodic, mild postural and tremor-like action dyskinesias in the arms. At the age of 15 years, mainly due to the drug-resistant absence seizures, we performed the molecular analysis of the SLC2A1 gene. The polymerase chain reaction sequencing of all exons revealed a nucleotide deletion in heterozygosity, "c.1336_1338del", causing the loss of one amino acid (isoleucine: p.Ile446del). Genetic testing was negative in both parents. We chose not to give the lumbar puncture to avoid causing the patient excessive discomfort. A ketogenic diet was started and we noted a fast, marked clinical improvement. The boy became more responsive and active, while absence seizures and headache frequency decreased. However, patient's compliance with the prescribed dietary regimen was so poor that after 1 year we decided to stop the diet. Only a few days after the discontinuation, the boy showed clinical worsening, which made him willing to resume the diet.
Figure 1: EEG recording, at the age of 14 years, showing diffuse bilateral and frontal dominant spike and wave discharges during wakefulness: open eyes on the left, closed eyes on the right

Click here to view
Figure 2: EEG recording, at the age of 14 years, showing diffuse bilateral spikes and waves during hyperpnea, once associated (see arrows) with a brief absence seizure

Click here to view



   Discussion Top


A constant supply of glucose is the most important source of energy for the brain. Therefore, GLUT1 deficiency syndrome could be considered as a brain energy failure prototype. During last years the classic phenotype of this syndrome, as originally reported, has expanded. Also the three following clinical pictures have been described: (a) carbohydrate-responsive phenotype, characterized by clinical worsening (motor and mental performance, seizures) with fasting and improvement with carbohydrate intake; (b) movement disorder without epilepsy, characterized by ataxia, dystonia, spasticity, mild delay of motor and mental development, normal or decelerated head growth; (c) paroxysmal exertion-induced dyskinesias (dystonia, choreoathetosis, ballism) and epilepsy. [2]

The case we have described shows an atypical phenotype of GLUT1 deficiency syndrome. No movement disorders were present (except for slight tremor after antiepileptic therapy start, probably a side effect of antiepileptic drugs), nor decrease of head circumference has been detected. The phenotype of our patient does not fully fit in any of the clinical pictures described so far in association with GLUT1 deficiency. In 2010, Leen et al. reported 10 cases with the so-called late-onset classical phenotype, but only in one of them movement disorders were absent and the reported features of seizures were different compared to those of our patient. [8] It is true that epilepsy with the absence seizures is among those most frequently described in GLUT1 deficiency syndrome, but more often it has an early onset (before the age of 4), while in the forms with later onset, as in our patient, the combination of drug-resistant absence seizures (without other types of seizures) and mental retardation, present in the case we have reported, has not been described. [7],[9],[10],[11],[12] Considering the findings of our patient's EEG (initially normal, then clearly pathological), our data confirm what Pong et al. stated, [7] namely that in the same individual, affected by this disorder, EEG picture could change over time. Our case report suggests that, in the lack of a better definition of the possible phenotypes associated with GLUT1 deficiency, there is a risk of underestimating the actual occurrence of the disease. Especially because of the atypical phenotypes, still today a high number of cases probably go undiagnosed. This fact has important implications also for the treatment, because a ketogenic diet, that should begin as soon as possible, could significantly improve the quality of life of these patients, while classic antiepileptic drugs usually fail. In fact, a high-fat diet leads to the production of ketone bodies bypassing the GLUT1 deficiency and providing an alternative source of energy to the brain. [1],[2],[3],[4],[5],[6] Incidentally, we emphasize that the exact pathogenetic mechanism of the formation of cataracts, also present in our patient, is currently unknown. [6]

In conclusion, clinical phenotype of GLUT1 deficiency syndrome needs further investigations. It is recommended to consider this diagnostic hypothesis in any case with an unexplained neurological disorder, [2],[11] also when, as in our case, a main clinical feature consists of drug-resistant seizures associated with a global developmental delay, even in the lack of a movement disorder, according to Klepper suggestions. [4]


   Acknowledgments Top


The authors would like to thank Massimo Armaroli and Elena Zoni for technical assistance and Cecilia Baroncini for linguistic support.

 
   References Top

1.De Vivo DC, Trifiletti RR, Jacobson RI, Ronen GM, Behmand RA, Harik SI. Defective glucose transport across the blood-brain barrier as a cause of persistent hypoglycorrhachia, seizures, and developmental delay. N Engl J Med 1991;325:703-9.  Back to cited text no. 1
    
2.Brockmann K. The expanding phenotype of GLUT1-deficiency syndrome. Brain Dev 2009;31:545-52.  Back to cited text no. 2
[PUBMED]    
3.Verrotti A, D′Egidio C, Agostinelli S, Gobbi G. Glut1 deficiency: When to suspect and how to diagnose? Eur J Paediatr Neurol 2012;16:3-9.  Back to cited text no. 3
    
4.Klepper J. GLUT1 deficiency syndrome in clinical practice. Epilepsy Res 2012;100:272-7.  Back to cited text no. 4
[PUBMED]    
5.De Giorgis V, Veggiotti P. GLUT1 deficiency syndrome 2013: Current state of the art. Seizure 2013;22:803-11.  Back to cited text no. 5
    
6.Pearson TS, Akman C, Hinton VJ, Engelstad K, De Vivo DC. Phenotypic spectrum of glucose transporter type 1 deficiency syndrome (Glut1 DS). Curr Neurol Neurosci Rep 2013;13:342.  Back to cited text no. 6
    
7.Pong AW, Geary BR, Engelstad KM, Natarajan A, Yang H, De Vivo DC. Glucose transporter type I deficiency syndrome: Epilepsy phenotypes and outcomes. Epilepsia 2012;53:1503-10.  Back to cited text no. 7
    
8.Leen WG, Klepper J, Verbeek MM, Leferink M, Hofste T, van Engelen BG, et al. Glucose transporter-1 deficiency syndrome: The expanding clinical and genetic spectrum of a treatable disorder. Brain 2010;133:655-70.  Back to cited text no. 8
    
9.Suls A, Mullen SA, Weber YG, Verhaert K, Ceulemans B, Guerrini R, et al. Early-onset absence epilepsy caused by mutations in the glucose transporter GLUT1. Ann Neurol 2009;66:415-9.  Back to cited text no. 9
    
10.Mullen SA, Suls A, De Jonghe P, Berkovic SF, Scheffer IE. Absence epilepsies with widely variable onset are a key feature of familial GLUT1 deficiency. Neurology 2010;75:432-40.  Back to cited text no. 10
    
11.Anand G, Padeniya A, Hanrahan D, Scheffer H, Zaiwalla Z, Cox D, et al. Milder phenotypes of glucose transporter type 1 deficiency syndrome. Dev Med Child Neurol 2011;53:664-8.  Back to cited text no. 11
    
12.Striano P, Weber YG, Toliat MR, Schubert J, Leu C, Chaimana R, et al.; EPICURE Consortium. GLUT1 mutations are a rare cause of familial idiopathic generalized epilepsy. Neurology 2012;78:557-62.  Back to cited text no. 12
    


    Figures

  [Figure 1], [Figure 2]



 

Top
Print this article  Email this article
 
 
  Search
 
  
 
    Similar in PUBMED
   Search Pubmed for
   Search in Google Scholar for
 Related articles
    Article in PDF (777 KB)
    Citation Manager
    Access Statistics
    Reader Comments
    Email Alert *
    Add to My List *
* Registration required (free)  


    Abstract
   Introduction
   Case Report
   Discussion
   Acknowledgments
    References
    Article Figures

 Article Access Statistics
    Viewed18531    
    Printed39    
    Emailed1    
    PDF Downloaded664    
    Comments [Add]    

Recommend this journal