Movement disorders in GLUT1 deficiency syndrome: a systematic review of the literature

Movement disorders (MDs) are a prominent feature of GLUT1 Deficiency Syndrome (GLUT1DS), a rare and treatable neurometabolic disorder caused by impaired glucose transport across the blood-brain barrier. We aimed to provide a comprehensive overview of the prevalence, clinical features, and treatment response of MDs in GLUT1DS.

A systematic review was conducted across five databases in accordance with PRISMA guidelines. The protocol was registered in PROSPERO (CRD42025644449). Studies reporting individual patient data on MDs in GLUT1DS were included. Descriptive and comparative analyses were performed.

Of 1178 records screened, 68 studies were included, comprising 94 published patients and two additional unpublished cases (n = 96). MDs were the presenting symptom in 34.4% of cases. The most frequent phenotypes were paroxysmal dyskinesias (63.5%) and ataxia (47.9%). Patients with MD-onset showed a later age at onset and fewer cognitive features. Non-missense variants were associated with earlier disease onset and a higher frequency of ataxia, whereas missense variants were independently associated with paroxysmal dyskinesias (OR 3.02, 95% CI 1.09-8.35). Ketogenic dietary therapies were associated with improvement in motor symptoms in most reported cases, although outcome data were heterogeneous and non-standardized.

MDs in GLUT1DS are highly heterogeneous and frequently overlap, with distinct patterns across clinical and genetic subgroups. While ketogenic therapies appear beneficial for motor symptoms, current evidence is limited by methodological variability and potential reporting bias, highlighting the need for prospective studies with standardized outcome measures.