Objective: To determine whether REM sleep behavior disorder (RBD) and other sleep abnormalities occur in carriers of the p.A53T alpha-synuclein gene (SNCA) mutation, the prototypical genetic synucleinopathy.

Background: RBD is defined as REM sleep without atonia (RWA) plus dream enactment behavior, documented either by medical history or by polysomnography (PSG). Sleep disorders and especially RBD may occur in association with neurodegenerative diseases, mainly a-synucleinopathies such as Parkinson’s disease (PD). In idiopathic PD, RBD may precede the motor manifestations of the disease.

Method: We recruited p.A53T mutations carriers – patients and/or their relatives- from our Movement Disorders outpatient clinics. DNA was extracted from peripheral blood, and the presence of the p.A53T mutation in the SNCA gene was examined. We have accordingly assessed 15 p.A53T carriers (10 manifesting PD and 5 asymptomatic carriers) with  simultaneous Video/PSG recording, Epworth Sleepiness Scale in order to assess the daytime sleepiness , RBD Screening Questionnaire (RBDSQ) to assess the most prominent clinical features of RBD and  Montreal Cognitive Assessment in order to assess the mental state of the subject (MOCA). We also questioned them whether they were treated with antidepressants  at the time of the study.

Results: 9/10 PD carriers had evidence of sleep disorder in PSG : In 4/10 PSG showed RBD (2 were treated with antidepressants and only 2 scored > 5 in RBDSQ), in 4/10 PSG showed RWA (only 1 scored >5 in RBDSQ)  and in 1/10 showed PLM. As far as asymptomatic carriers are concerned, only 1/5 manifested RWA in PSG, but this subject was treated with antidepressants at the time of the study.

Conclusion: RBD or RWA occur in the majority of PD p.A53T carriers, possibly at a higher percentage compared to idiopathic PD. Our results contrast with other genetic forms of PD, where RBD features appear to be rare. The fact that most of the asymptomatic carriers had no evidence of a sleep disorder may be a sign of different temporal evolution of RBD manifestations compared to idiopathic PD, or may reflect that such carriers have not yet reached the prodromal phase of the disease.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/sleep-aspects-on-video-polysomnography-in-p-a53t-snca-mutation-carriers/