Study of paediatric patients with the clinical and biochemical phenotype of glucose transporter type 1 deficiency syndrome

Classic Ketogenic Diet and Modified Atkins Diet in SLC2A1 Positive and Negative Patients with Suspected GLUT1 Deficiency Syndrome: A Single Center Analysis of 18 Cases

Background: Glucose transporter type 1 deficiency syndrome (GLUT1DS) is caused by mutations in the SLC2A1 gene and produces seizures, neurodevelopmental impairment, and movement disorders. Ketogenic dietary therapies (KDT) are the gold standard treatment. Similar symptoms may appear in SLC2A1 negative patients. The purpose is to evaluate the effectiveness of KDT in children with GLUT1DS suspected SLC2A1 (+) and (-), side effects (SE), and the impact on patients nutritional status. Methods: An observational descriptive study was conducted to describe 18 children (January 2009–August 2020). SLC2A1 analysis, seizures, movement disorder, anti-epileptic drugs (AEDS), anthropometry, SE, and laboratory assessment were monitored baseline and at 3, 6, 12, and 24 months after the onset of KDT. Results: 6/18 were SLC2A1(+) and 13/18 had seizures. In these groups, the age for debut of symptoms was higher. The mean time from debut to KDT onset was higher in SLC2A1(+). The modified Atkins diet (MAD) was used in 12 (5 SLC2A1(+)). Movement disorder improved (4/5), and a reduction in seizures >50% compared to baseline was achieved in more than half of the epileptic children throughout the follow-up. No differences in effectiveness were found according to the type of KDT. Early SE occurred in 33%. Long-term SE occurred in 10, 5, 7, and 5 children throughout the follow-up. The most frequent SE were constipation, hypercalciuria, and hyperlipidaemia. No differences in growth were found according to the SLC2A1 mutation or type of KDT. Conclusions: CKD and MAD were effective for SLC2A1 positive and negative patients in our cohort. SE were frequent, but mild. Permanent monitoring should be made to identify SE and nutritional deficits.

Movement Disorders in Inherited Metabolic Diseases in Children

Movement disorders are one of the important neurological manifestations of inherited metabolic disorders. Important clues to the presence of an underlying inborn error of metabolism are early onset, presence of neuroregression or degeneration, parental consanguinity, sibling affection, paroxysmal events, waxing and waning course, skin or hair changes, absence of a perinatal insult or any structural cause, and presence of identifiable triggers. It is particularly important to recognize this class of movement disorders as several of them are eminently treatable and may often need disease-specific therapy besides symptomatic treatment. The current review focusses on the movement disorders associated with inherited metabolic defects in children, with emphasis on treatable disorders.