Occurrence of GLUT1 deficiency syndrome in patients treated with ketogenic diet

Dietary management and access to treatment for patients with glucose deficiency syndrome type 1: an overview review with focus on the European regulatory framework

BACKGROUND

Glut-1 deficiency Syndrome (GLUT-1 DS) is a rare disease caused by a mutation in the SLC2A1 gene that codes for the glucose transporter protein GLUT-1 DS. Currently, there is no indicated drug therapy for this condition and ketogenic diet (KD) is the most effective remedy to treat it.

OBJECTIVE

The objective of this study was to review the published literature that evaluated the effectiveness of KD in the dietary management of GLUT-1 DS syndrome, describing the state-of-the-art the treatment pathway for patients with GLUT-1 DS syndrome in light of the current European regulatory framework within the National Health Services.

METHODS

The literature search was carried out on September 10, 2023, and all studies conducted in humans diagnosed with GLUT-1 deficiency syndrome and treated with KD were included.

RESULTS

A total of 156 scientific papers have been extracted. Applying the exclusion criteria, 38 articles have been considered eligible. In 29 out of 38 studies, the main outcome for determining the efficacy of KD was the measurement of the number of epileptic seizures, demonstrating that patients treated with KD experienced improvements with a clear reduction in the number of epileptic attacks. Currently, in the European Union, only one country provides full reimbursement by the national health system for KD.

DISCUSSION

Although they are crucial for the treatment of GLUT-1 DS, according with current food regulations, KD are not evaluated on the basis of an unambiguous efficacy result, but only on the basis of safety. As a result, it is desirable to carry out clinical studies in the coming years based on the determination of efficacy in target populations, also in view of the marketing of these products on the European market.

Lipid Metabolism at the Nexus of Diet and Tumor Microenvironment

Obesity is a leading contributing factor to cancer development worldwide. Epidemiological evidence suggests that diet affects cancer risk and also substantially alters therapeutic outcome. Therefore, studying the impact of diet in the development and treatment of cancer should be a clinical priority. In this Review, we set out the evidence supporting the role of lipid metabolism in shaping the tumor microenvironment (TME) and cancer cell phenotype. We will discuss how dietary lipids can impact phenotype thereby affecting disease trajectory and treatment response. Finally, we will posit potential strategies on how this knowledge can be exploited to increase treatment efficacy and patient survival.

Cognitive benefits of the ketogenic diet in patients with epilepsy: A systematic overview

The ketogenic diet (KD) has been found to be effective in reducing seizures in patients with treatment-refractory epilepsy. Less attention has been paid to additional cognitive benefits of KD. The aim of the present paper was to provide a comprehensive overview of the studies reporting effects on cognition after KD treatment in adults and children with epilepsy. To address this aim, the clinical literature on cognitive effects of KD in patients with epilepsy was reviewed using a systematic approach. We conclude that using subjective assessments of the patient's experience, cognitive improvements are frequently reported during KD treatment in the domains of alertness, attention, and global cognition. Studies that used objective neuropsychological tests confirmed benefits on alertness but found no improvement in global cognition. There are indications that these improvements are caused by both seizure reduction and direct effects of KD on cognition. The improvements appear to be unrelated to medication reduction, age when KD is started, type of KD, and sleep improvement. The findings in the present overview contribute to a better understanding of the beneficial effects of KD in patients with epilepsy.

Prevalence of Genetic Disorders and GLUT1 Deficiency in a Ketogenic Diet Clinic

Between July of 2012 and December of 2014, 39 patients were enrolled prospectively to investigate the prevalence of glucose transporter 1 (GLUT1) deficiency in a ketogenic diet clinic. None of them had GLUT1 deficiency. All patients seen in the same clinic within the same period were reviewed retrospectively. A total of 18 of these 85 patients had a genetic diagnosis, including GLUT1 deficiency, pathogenic copy number variants, congenital disorder of glycosylation, neuronal ceroid lipofuscinosis type II, mitochondrial disorders, tuberous sclerosis, lissencephaly, and SCN1A-, SCN8A-, and STXBP1-associated epileptic encephalopathies. The prevalence of genetic diagnoses was 21% and prevalence of GLUT1 deficiency was 2.4% in our retrospective cohort study.

Paroxysmal Nonepileptic Events in Glut1 Deficiency

Movement disorders are a major feature of Glut1 deficiency. As recently identified in adults with paroxysmal exercise‐induced dystonia, similar events were reported in pediatric Glut1 deficiency. In a case series, parent videos of regular motor state and paroxysmal events were requested from children with Glut1 deficiency on clinical follow‐up. A questionnaire was sent out to 60 families. Videos of nonparoxysmal/paroxysmal states in 3 children illustrated the ataxic‐dystonic, choreatiform, and dyskinetic‐dystonic nature of paroxysmal events. Fifty‐six evaluated questionnaires confirmed this observation in 73% of patients. Events appeared to increase with age, were triggered by low ketosis, sleep deprivation, and physical exercise, and unrelated to sex, hypoglycorrhachia, SLC2A1 mutations, or type of ketogenic diet. We conclude that paroxysmal events are a major clinical feature in Glut1 deficieny, linking the pediatric disease to adult Glut1D‐associated exercise‐induced paroxysmal dyskinesias.

Genetic screening and diagnosis in epilepsy?

PURPOSE OF REVIEW

Genetic discovery has been extremely rapid over the last year, with many new discoveries illuminating novel mechanisms and pathways. In particular, the application of whole exome and whole genome sequencing has identified many new genetic causes of the epilepsies. As such methods become increasingly available, it will be critical for practicing neurologists to be acquainted with them. This review surveys some important developments over the last year.

RECENT FINDINGS

The range of tests available to the clinician is wide, and likely soon to be dominated by whole exome and whole genome sequencing. Both whole exome and whole genome sequencing have usually proven to be more powerful than most existing tests. Many new genes have been implicated in the epilepsies, with emerging evidence of the involvement of particular multigene pathways.

SUMMARY

For the practicing clinician, it will be important to appreciate progress in the field, and to prepare for the application of novel genetic testing in clinical practice, as genetic data are likely to contribute importantly for many people with epilepsy.

Favourable response to ketogenic dietary therapies: undiagnosed glucose 1 transporter deficiency syndrome is only one factor

AIM

We aimed to determine whether response to ketogenic dietary therapies (KDT) was due to undiagnosed glucose transporter type 1 deficiency syndrome (GLUT1-DS).

METHOD

Targeted resequencing of the SLC2A1 gene was completed in individuals without previously known GLUT1-DS who received KDT for their epilepsy. Hospital records were used to obtain demographic and clinical data. Response to KDT at various follow-up points was defined as seizure reduction of at least 50%. Seizure freedom achieved at any follow-up point was also documented. Fisher's exact and gene-burden association tests were conducted using the PLINK/SEQ open-source genetics library.

RESULTS

Of the 246 participants, one was shown to have a novel variant in SLC2A1 that was predicted to be deleterious. This individual was seizure-free on KDT. Rates of seizure freedom in cases without GLUT1-DS were below 8% at each follow-up point. Two cases without SLC2A1 mutations were seizure-free at every follow-up point recorded. No significant results were obtained from Fisher's exact or gene-burden association tests.

INTERPRETATION

A favourable response to KDT is not solely explained by mutations in SLC2A1. Other genetic factors should be sought to identify those who are most likely to benefit from dietary treatment for epilepsy, particularly those who may achieve seizure freedom.

Neurobiochemical mechanisms of a ketogenic diet in refractory epilepsy

A ketogenic diet is an important therapy used in the control of drug-refractory seizures. Many studies have shown that children and adolescents following ketogenic diets exhibit an over 50% reduction in seizure frequency, which is considered to be clinically relevant. These benefits are based on a diet containing high fat (approximately 90% fat) for 24 months. This dietary model was proposed in the 1920s and has produced variable clinical responses. Previous studies have shown that the mechanisms underlying seizure control involve ketone bodies, which are produced by fatty acid oxidation. Although the pathways involved in the ketogenic diet are not entirely clear, the main effects of the production of ketone bodies appear to be neurotransmitter modulation and antioxidant effects on the brain. This review highlights the impacts of the ketogenic diet on the modulation of neurotransmitters, levels of biogenic monoamines and protective antioxidant mechanisms of neurons. In addition, future perspectives are proposed.