From triggers to targets: Navigating the precision neurology era of pediatric dyskinesias

Notice: Blog posts are not subject to review by MedLink Neurology’s Editorial Board.

Author: Joaquin A Pena MD

Introduction: the end of symptom-based silos

For decades, we approached pediatric paroxysmal dyskinesias through the lens of clinical triggers. Since the seminal 1995 classification by Demirkiran and Jankovic, clinicians grouped these rare, episodic movement disorders into four categories: kinesigenic, non-kinesigenic, exercise-induced, and hypnogenic. Although this framework was necessary at the bedside, it often left us in the dark about the underlying biology.

Today, the field is undergoing a paradigm shift. We are moving from symptom-based labeling to gene-informed care. Advancements in next-generation sequencing have shown that clinical triggers are often poor predictors of molecular etiology. With the discovery of more than 38 genes and a diagnostic yield now reaching 35% to 50% for pediatric paroxysmal dyskinesia, we are finally entering the era of precision neurology, in which a genetic diagnosis directly guides the therapeutic path.

Mechanisms of action: from triggers to pathophysiology

The "old world" classification relied on triggers such as sudden movement or caffeine. The "new world" classifies pediatric paroxysmal dyskinesias by their pathophysiological mechanisms: synaptopathies, channelopathies, and transportopathies or energy deficits.

• Synaptopathies. The most common form involves PRRT2 (proline-rich transmembrane protein 2). PRRT2 is located presynaptically and interacts with the SNARE complex (specifically SNAP25), thereby regulating calcium-dependent neurotransmitter release. Mutations lead to an excitation/inhibition imbalance, particularly in the cerebellum, resulting in network hyperexcitability that manifests as paroxysmal events. PNKD (the gene) also falls under this category, regulating neurotransmitter exocytosis in dopaminergic neurons.
• Channelopathies. Initially, we suspected that all pediatric paroxysmal dyskinesias were channelopathies, such as periodic paralysis. Although PRRT2 proved this wrong, true channelopathies, such as SCN8A and KCNMA1 (a potassium channel), do exist and often present with a mix of epilepsy and dyskinesia.
• Transportopathies and energy deficits. This category represents a critical diagnostic "must-not-miss" group. SLC2A1 mutations cause GLUT1 deficiency syndrome, in which glucose fails to cross the blood-brain barrier. Other energy-related genes include ECHS1 (valine metabolism) and the pyruvate dehydrogenase complex, which is implicated in metabolic stress-triggered motor paroxysms.

Improved genetic diagnostics: the clinician’s new roadmap

Historical approaches favored single-gene testing, but phenotypic pleiotropy (where a single gene can produce multiple phenotypes, and a single phenotype can arise from multiple genes) has rendered that strategy obsolete. The field is shifting from symptom-based labeling to gene-informed care. The current recommended diagnostic algorithm begins with a thorough clinical history and quickly pivots to broad-based genetic testing.

1. Clinical clues. Onset typically occurs between 3.9 and 8.8 years. Male sex is more commonly reported (63.4%).
2. The panel-first approach. For isolated pediatric paroxysmal dyskinesia phenotypes, a comprehensive "paroxysmal movement disorder" or "episodic disorder" panel is preferred because it provides higher-resolution coverage of known genes, such as PRRT2, SLC2A1, and ADCY5.
3. Whole-exome or whole-genome sequencing. If the initial panel is negative or the phenotype is "plus" (eg, intellectual disability or epilepsy), whole-exome or whole-genome sequencing is indicated.
4. Chromosomal microarray. This remains essential for patients with complicated phenotypes (facial dysmorphism, developmental delay) to detect copy-number variants, such as the 16p11.2 deletion, which encompasses the PRRT2 locus.

Clinical efficacy: the power of genotype-guided treatment

The most compelling argument for the shift to gene-informed care is the dramatic efficacy of targeted therapies.

• PRRT2 (sodium channel blockers). Patients with PRRT2-related paroxysmal kinesigenic dyskinesia show a "dramatic" or "exquisite" response to low-dose carbamazepine or oxcarbazepine. Doses of 50 to 600 mg/day can achieve complete symptom resolution in most cases.
• SLC2A1 (ketogenic diet). In paroxysmal exercise-induced dyskinesia cases caused by GLUT1 deficiency, traditional antiseizure drugs often fail. However, the ketogenic diet provides the brain with an alternative energy source (ketone bodies), bypassing the glucose transport defect and significantly improving movement disorders.
• ADCY5 (caffeine). A recent breakthrough concerns ADCY5-related dyskinesia. Caffeine, an adenosine A2A receptor antagonist, has been shown to markedly reduce both daytime and nocturnal paroxysms in approximately 87% of patients.
• GCH1 (levodopa). While rare, some paroxysmal exercise-induced dyskinesia phenotypes are variants of dopa-responsive dystonia, in which levodopa can induce remission.

Adverse events and comparisons with existing treatments

The cost of misdiagnosis is not just financial; it is a burden of "useless and sometimes even injurious treatment." A striking example is a 59-year-old woman who was misdiagnosed with drug-resistant epilepsy for 57 years, treated with countless antiseizure medications, and only later diagnosed with ADCY5-related dyskinesia via whole-exome sequencing, after which she found relief with caffeine.

Compared with symptom-based treatment, gene-informed care avoids the side effects of unnecessary, high-dose antiseizure medications. For example, in SCN2A-related disorders, determining whether a variant is gain-of-function or loss-of-function is critical because sodium channel blockers can either help or harm the patient, depending on the genotype.

Guidelines and recommendations: key diagnostic "red flags"

Clinicians should maintain a high level of suspicion for secondary causes when "red flags" are present: adult onset, variable triggers, an abnormal interictal examination, or an abnormal MRI.

For primary pediatric paroxysmal dyskinesias, we now recommend:

• Video documentation. Given the paroxysmal nature, home video recordings are often more valuable than in-clinic examinations.
• Gene-specific monitoring. If a PRRT2 mutation is identified, clinicians must screen for associated comorbidities, including Infantile convulsions with choreoathetosis syndrome, hemiplegic migraine, or episodic ataxia.
• Trigger avoidance. Although gene-informed medication is the primary approach, avoiding specific triggers (eg, caffeine or alcohol in PNKD mutations, fasting in SLC2A1) remains a cornerstone of management.

Ongoing controversies: the paroxysmal hypnogenic dyskinesia and episodic ataxia overlap

The field is currently debating the boundaries of pediatric paroxysmal dyskinesia.

1. The return of paroxysmal hypnogenic dyskinesia. Paroxysmal hypnogenic dyskinesia was previously removed from pediatric paroxysmal dyskinesia classifications because many cases were found to be nocturnal frontal lobe epilepsy. However, the discovery that PRRT2 and ADCY5 can both present with sleep-triggered dyskinesia has led to the re-inclusion of paroxysmal hypnogenic dyskinesia as a true pediatric paroxysmal dyskinesia subtype.
2. Pediatric paroxysmal dyskinesias versus episodic ataxia. The boundaries are blurring. PRRT2 and SLC2A1 mutations can present with ataxia, and KCNA1 (traditionally an EA1 gene) can present with paroxysmal dyskinesia. This reinforces the need to move away from rigid clinical labels toward a molecular-mechanistic classification.

Future directions: closing the research gaps

Despite our progress, a significant proportion of patients remain undiagnosed. Future research must prioritize:

• Non-coding variants. Whole-exome sequencing misses deep intronic and regulatory variants; long-read whole-genome sequencing may be the next frontier.
• Somatic mosaicism. As seen in ADCY5, some mutations may be present only in certain cell lines, requiring deeper sequencing.
• Precision therapeutics. We need randomized controlled trials for many of these newer gene-treatment pairings, particularly for ADCY5 and GNAO1.

As child neurologists, we must lead this transition. By prioritizing genetic clarity over clinical labels, we can offer our patients a path to remission once thought impossible.

Bibliography

Bavdhankar KP, Agarwal PA. Paroxysmal movement disorders: an update on clinical approach, pathophysiology and genetic underpinnings. Ann Mov Disord 2025;8(1):14-36.

Ebrahimi-Fakhari D, Kang KS, Kotzaeridou U, et al. Child neurology: PRRT2-associated movement disorders and differential diagnoses. Neurology 2014 83(18) 1680-3. PMID 25349275

Landolfi A, Barone P, Erro R. The spectrum of PRRT2-associated disorders: update on clinical features and pathophysiology. Front Neurol 2021;12:629747. PMID 33746883

Moreno-Estébanez A, Sanchez-Orvath M, Marinas A, et al. Pearls & Oy-sters: ADCY5-related dyskinesia: from a longstanding misdiagnosis of drug-resistant epilepsy. Neurology 2025;104(10):e213661. PMID 40300124

Pisano G, Gnazzo M, Sigona G, et al. Paroxysmal dyskinesias in pediatric age: a systematic review. J Clin Med 2025;14(17)5925. PMID 40943684

Are you interested in contributing a post or becoming a guest blogger for MedLink? Contact us at editorial@medlink.com.