Major clinical characteristics and response to standard therapy appear to be similar among patients with 22q11.2 deletion syndrome (22q11.2 DS)-associated Parkinson disease (PD) and those with idiopathic PD, although treatment of preexisting psychotic illness may delay diagnosis in individuals with 22q11.2 DS-PD, according to the results of an international observational study published in Neurology.
The investigators of the current study characterized the clinical and neuroimaging features of 45 individuals with concurrent PD and 22q11.2 DS. Mean follow-up occurred at 7.5±4.1 years. Mean age at the development of motor symptoms was 39.5±8.5 years, and 71.4% of the cases had early-onset PD (<45 years of age).
There was a typical male abundance of patients with 22q11.2 DS-PD, with 71.1% (32 of 45) of cases being reported among the study cohort. Those with 22q11.2 DS-PD presented and progressed with hallmark motor symptoms, reduced striatal dopamine transporter binding on molecular imaging, and an initial positive response to levodopa (93.3%).
Although patients with both idiopathic and 22q11.2 DS forms of PD had a similar age at onset, the diagnosis of PD was delayed significantly in patients who had a history of antipsychotic therapy compared with those who were antipsychotic naive (median time from motor symptom onset to PD diagnosis, 5 years vs 1 year, respectively; P =.001). Preexisting psychiatric disorders and mood and anxiety disorders were common in those with 22q11.2 DS-PD (24.5% vs 31.1%, respectively), as were the development of early dystonia and a history of seizures (19.4% vs 33.3%, respectively).
The investigators concluded that additional prospective clinical, neuropathologic, molecular, and animal studies should help to further clarify the pathogenesis of this molecular subtype of PD, thus indicating how well 22q11.2 DS-PD might act as a genetic model for other forms of the disease. An index of suspicion, along with vigilance foir complex comorbidities, may assist clinicians in recognizing those patients who should be prioritized for genetic testing.
Boot E, Butcher NJ, Udow S, et al; on behalf of the International Research Group on 22q11.2DS-associated Parkinson’s Disease. Typical features of Parkinson disease and diagnostic challenges with microdeletion 22q11.2 [published online May 11, 2018]. Neurology. doi: 10.1212/WNL.0000000000005660