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Introduction
The human glucose transporter type 1 protein (GLUT1) catalyses the facilitative diffusion of glucose into erythrocytes and is responsible for glucose transport into the brain.1 Heterozygous mutations in SLC2A1, encoding GLUT1, may result in paucity of cerebral glucose, marked depletion of brain energy and neuroglycopaenia, causing Glut1 deficiency syndrome (Glut1 DS).2 Takahashi et al 3 reported several mutations in SLC2A1 as a cause of paroxysmal exercise‐induced dyskinesia. Here, we report a patient with paroxysmal exercise‐induced dyskinesia and gait impairment that started in childhood. This was found to be due to a novel SLC2A1 variant NM_006516.4: c.671C>T p.(Ala224Val) occurring de novo. We discuss the diagnostic process that enabled us to prove the variant’s pathogenicity.
Case report
A 41-year-old right-handed woman reported episodic motor dysfunction in her legs. She had distinctive attacks when walking since aged 8 years. Episodes were stereotyped, in which she would find her legs giving way or behaving erratically—requiring support. Typically, attacks lasted for 20 min. The frequency was variable, with several attacks over a few days to being unaffected for years. Attacks occurred inevitably when walking, and, generally, she required 20 min of rest before recovering sufficiently to walk again. Attacks were associated with stress and heat. She had taken acetazolamide 250 mg two times per day since childhood and felt that this helped. Interestingly, during her two pregnancies (when not taking acetazolamide) she was attack-free. There was no correlation with eating, fasting or caffeine intake. There was no history of neurodevelopmental delay or seizures and no family history of similar episodes. Her parents were non-consanguineous …
Footnotes
Contributors RM: review of patient: ongoing follow up and diagnostic tests; manuscript: writing of first draft. DT: review of patient: diagnostic tests; manuscript: writing of first draft. RDS review of patient: initial clinical consultation and ongoing follow up; genetic analysis; manuscript: review and critique. SM: genetic analysis; manuscript: review and critique. RM is the guarantor.
Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.
Competing interests None declared.
Provenance and peer review Not commissioned; externally reviewed by Francesca Magrinelli, London, UK.
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