ADCY5 Dyskinesia

Clinical characteristics: ADCY5 dyskinesia is a hyperkinetic movement disorder (more prominent in the face and arms than the legs) characterized by infantile to late-adolescent onset of chorea, athetosis, dystonia, myoclonus, or a combination of these. To date, affected individuals have had overlapping (but not identical) manifestations with wide-ranging severity. The facial movements are typically periorbital and perioral. The dyskinesia is prone to episodic or paroxysmal exacerbation lasting minutes to hours, and may occur during sleep. Precipitating factors in some persons have included emotional stress, intercurrent illness, sneezing, or caffeine; in others, no precipitating factors have been identified. In some children, severe infantile axial hypotonia results in gross motor delays accompanied by chorea, sometimes with language delays. The overall tendency is for the abnormal movements to stabilize in early middle age, at which point they may improve in some individuals; less commonly, the abnormal movements are slowly progressive, increasing in severity and frequency.

Diagnosis/testing: The diagnosis of ADCY5 dyskinesia is established in a proband with a hyperkinetic movement disorder (in the absence of structural brain abnormalities) and a heterozygous pathogenic or likely pathogenic variant (or, rarely, biallelic pathogenic or likely pathogenic variants) in ADCY5 identified by molecular genetic testing.

Management: Treatment of manifestations: Management by multidisciplinary specialists, including a neurologist or neurogeneticist, cardiologist, physical therapist, social worker, speech and language pathologist, and other specialists is recommended as needed. Anecdotally, medications have had variable effect in suppressing debilitating symptoms. Treatment should be determined by the individual's physician, taking into account potential risk/benefit, other medical conditions, allergies, and potential drug-drug interactions. Response to medication is difficult to evaluate because some individuals have long periods (weeks) of remission of the dyskinesia. Physical and occupational therapy may help maintain mobility and function. Speech and language therapy for dysarthria may include alternative communication methods. Cognitive impairment and psychiatric manifestations are managed per standard practice.

Surveillance: Routine follow up of neurologic involvement, dysarthria, oculomotor involvement, musculoskeletal involvement, activities of daily living, cognitive impairment, and psychiatric manifestations.

Pregnancy management: Potential teratogenic effects of medications given for treatment of ADCY5 dyskinesia should be discussed with affected women of childbearing age, ideally prior to conception.

Genetic counseling: ADCY5 dyskinesia is typically inherited in an autosomal dominant (AD) manner. Autosomal recessive (AR) inheritance has been reported in two families.

AD inheritance. The majority of individuals diagnosed with ADCY5 dyskinesia represent simplex cases (i.e., a single affected family member) and have the disorder as the result of a de novo pathogenic variant. Each child of an individual with ADCY5 dyskinesia has a 50% chance of inheriting the pathogenic variant.

Both AD and AR inheritance. Once the ADCY5 pathogenic variant(s) have been identified in an affected family member, prenatal testing for a pregnancy at increased risk and preimplantation genetic testing for ADCY5 dyskinesia are possible.