Replication assessment of NUS1 variants in Parkinson's disease

Psychosis in Parkinson's Disease: A Lesson from Genetics

Psychosis in Parkinson's disease (PDP) represents a common and debilitating condition that complicates Parkinson's disease (PD), mainly in the later stages. The spectrum of psychotic symptoms are heterogeneous, ranging from minor phenomena of mild illusions, passage hallucinations and sense of presence to severe psychosis consisting of visual hallucinations (and rarely, auditory and tactile or gustatory) and paranoid delusions. PDP is associated with increased caregiver stress, poorer quality of life for patients and carers, reduced survival and risk of institutionalization with a significant burden on the healthcare system. Although several risk factors for PDP development have been identified, such as aging, sleep disturbances, long history of PD, cognitive impairment, depression and visual disorders, the pathophysiology of psychosis in PD is complex and still insufficiently clarified. Additionally, several drugs used to treat PD can aggravate or even precipitate PDP. Herein, we reviewed and critically analyzed recent studies exploring the genetic architecture of psychosis in PD in order to further understand the pathophysiology of PDP, the risk factors as well as the most suitable therapeutic strategies.

NUS1 and Epilepsy-myoclonus-ataxia Syndrome: An Under-recognized Entity?

Background:

Variants of the NUS1 gene have recently been linked to a spectrum of phenotypes including epilepsy, cerebellar ataxia, cortical myoclonus and intellectual disability (ID), and primary congenital defects of glycosylation.

Case Report:

We report a case of myoclonus epilepsy, mild cerebellar ataxia, and ID due to a new de-novo NUS1 missense variant (c.868C>T, p.R290C), and review the current literature of NUS1-associated clinical phenotypes.

Discussion:

Pathogenic variants of NUS1 are found in a rapidly growing number of cases diagnosed with myoclonus epilepsy and/or myoclonus-ataxia syndrome. NUS1 should be included in the genetic screening of undiagnosed forms of myoclonus, myoclonus-ataxia, and progressive myoclonus epilepsies.

Low-frequency and rare coding variants of NUS1 contribute to susceptibility and phenotype of Parkinson's disease

NUS1 has been recently identified as a candidate gene for Parkinson's disease (PD). Few studies have examined the association of NUS1 variants with PD susceptibility and phenotypes. In the first cohort, whole-exome sequencing was performed to identify variants in NUS1 exon-coding and exon-intron regions in 1542 cases and 1625 controls. 13 variants were totally detected, of which 10 rare variants and 3 low-frequency variants. Burden analysis showed that rare NUS1 variants significantly enriched in PD (p=0.016). We also performed a meta-analysis based on previous and our studies to correlate NUS1 mutations with PD susceptibility. Integrating our previous cohort (3210 cases and 2807 controls) and the first cohort identified the significant association of rs539668656 with PD risk (odds ratio (OR) = 2.82, p = 0.016). The genotype-phenotype association analysis showed that patients carrying rare variants, or rs539668656 were significantly associated with earlier onset age, depression, emotional impairment and severe disease condition. Our results support the role of NUS1 rare variants and rs539668656 towards PD susceptibility and phenotype.