Lesser motor disability in adulthood: A ten-year follow-up of a dyskinetic patient with ADCY5 mutation

Scoping Review on ADCY5-Related Movement Disorders

Background

Adenylyl cyclase 5 (ADCY5)-related movement disorder (ADCY5-RMD) is a rare, childhood-onset disease resulting from pathogenic variants in the ADCY5 gene. The clinical features, diagnostic options, natural history, and treatments for this disease are poorly characterized and have never been established through a structured approach.

Objective

This scoping review attempts to summarize all available clinical literature on ADCY5-RMD.

Methods

Eighty-seven articles were selected for inclusion in this scoping review. The majority of articles identified were case reports or case series.

Results

These articles demonstrate that patients with ADCY5-RMD suffer from permanent and/ or paroxysmal hyperkinetic movements. The paroxysmal episodes can be worsened by environmental triggers, in particular the sleep-wake transition phase in the early morning. Occurrence of nocturnal paroxysmal dyskinesias and perioral twitches are highly suggestive of the diagnosis when present. In the majority of patients intellectual capacity is preserved. ADCY5-RMD is considered a non-progressive disorder, with inter-individual variations in evolution with aging. Somatic mosaicism, mode of inheritance and the location of the mutation within the protein can influence phenotype.

Conclusions

The current evidence for therapeutic options for ADCY5-RMD is limited: caffeine, benzodiazepines and deep brain stimulation have been consistently reported to be useful in case reports and case series.

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Background Mutations in the adenylate cyclase 5 (ADCY5) gene are associated with childhood-onset paroxysmal dyskinesia.

Methods We report a new video-documented case of pediatric ADCY5-related dyskinesia with de novo ADCY5 mutation.

Results A boy born to nonconsanguineous parents after an uneventful pregnancy had developmental delay and hypotonia. At the age of 7 months, he presented with paroxysmal jerky–choreic–dystonic involuntary movements in wakefulness involving limbs, trunk, and face, exacerbated by emotional stimuli. These episodes gradually worsened in duration and frequency: at the age of 2.5 years, they occurred up to six times per day, and appeared also during sleep in prolonged bouts; the boy also had basal choreoathetoid–dystonic movements, hyperactivity, paraparetic–ataxic gait, generalized hypotonia with brisk tendon reflexes, drooling, and language delay with intellectual disability. Brain magnetic resonance imaging, electroencephalogram, electromyogram, eye review, metabolic investigations, oligoclonal bands, and autoantibodies were normal. Extensive genetic testing had not let to a diagnosis, until a heterozygous de novo mutation c.1252C > T (p.Arg418Trp) was identified in the ADCY5 gene. Clonazepam had partial effectiveness. The boy walked at the age of 3.5 years. At the age of 5 years, the paroxysmal movement disorder has slightly improved.

Conclusion ADCY5 mutations should be considered among the differential diagnoses of early-onset paroxysmal choreic–athetosic–myoclonic–dystonic movement disorder involving limbs, trunk, and face, in patients with global neurological impairment with hypotonia and developmental delay. Facial dyskinesias and exacerbation by drowsiness/sleep and emotional stimuli are important clues that may allow a timely recognition of the disorder and avoidance of unnecessary diagnostic investigations.