Study of an FBXO7 patient mutation reveals Fbxo7 and PI31 co-regulate proteasomes and mitochondria

Mutations in FBXO7 have been discovered associated with an atypical parkinsonism. We report here a new homozygous missense mutation in a paediatric patient that causes an L250P substitution in the dimerization domain of Fbxo7. This alteration selectively ablates the Fbxo7-PI31 interaction and causes a significant reduction in Fbxo7 and PI31 levels in patient cells. Consistent with their association with proteasomes, L250P patient fibroblasts have reduced proteasome activity and proteasome subunits. We also show PI31 interacts directly with the MiD49/51 fission adaptor proteins, and unexpectedly, PI31 acts as an adaptor enabling SCFFbxo7 ligase to ubiquitinate MiD49. Thus, the L250P mutation changes the function of Fbxo7 by altering its substrate repertoire. Although MiD49/51 expression was reduced in L250P patient cells, there was no effect on the mitochondrial network. However, patient cells had higher levels of ROS and reduced viability under stress. Our study shows that Fbxo7 and PI31 affect each other's functions in regulating both proteasomal and mitochondrial function and demonstrate a new function for PI31, as an adaptor for the SCFFbxo7 E3 ubiquitin ligase.

First delirium episode in Parkinson’s disease and parkinsonism: incidence, predictors, and outcomes

To define the incidence, predictors and prognosis of the first hospital delirium episode in Parkinson’s disease (PD) and atypical parkinsonism (AP), we identified the first hospital episode of delirium after diagnosis in the Parkinsonism Incidence in North-East Scotland (PINE) study, a prospective community-based incidence cohort of parkinsonism, using chart-based criteria to define delirium. Of 296 patients (189=PD, 107=AP [dementia with Lewy bodies, progressive supranuclear palsy, multiple system atrophy, vascular parkinsonism]), 152 developed delirium (PD = 98, AP = 54). Incidence of first hospital delirium episode per 100 person years was 8.1 (95% confidence interval [CI] 6.6–9.9) in PD and 18.5 (95% CI 13.9–24.7) in AP. Independent predictors of delirium were atypical parkinsonism (Hazard ratio [HR] vs PD = 2.83 [95% CI 1.60–5.03], age in PD but not in AP (HR for 10-year increase 2.29 [95% CI 1.74–3.02]), baseline MMSE (HR = 0.94 [95% CI 0.89–0.99]), APOE ε4 in PD (HR 2.16 [95% CI 1.15–4.08]), and MAPT H1/H1 in PD (HR 2.08 [95% CI 1.08–4.00]). Hazards of dementia and death after delirium vs before delirium were increased (dementia: HR = 6.93 [95% CI 4.18–11.48] in parkinsonism; death: HR = 3.76 [95% CI 2.65–5.35] in PD, 1.59 [95% CI 1.04–2.42] in AP). Delirium is a common non-motor feature of PD and AP and is associated with increased hazards of dementia and mortality. Whether interventions for early identification and treatment improve outcomes requires investigation.

Ankylosing Spondylitis: A Risk Factor for Parkinsonism—A Nationwide Population-Based Study

Background: Ankylosing spondylitis (AS) is an immune-mediated, chronic inflammatory rheumatic disorder. The etiology of Parkinson’s disease (PD) is multifactorial; however, inflammation is receiving an increasing amount of attention as an underlying cause of the neurodegenerative process of PD. Objective: We performed a nationwide longitudinal, population-based matched cohort study to assess the association with the later development of parkinsonism in Korea. Methods: This study was conducted using records from the Health Insurance Review and Assessment Service database. The cumulative incidence rate of PD was estimated. Fine–Gray subdistribution hazard models were used to identify hazards associated with PD development based on the presence of AS. Exposure to anti-inflammatory drugs was measured and analyzed to determine the protective effect of these medications. Additionally, the hazard ratio (HR) for atypical parkinsonism was estimated. Results: The results of the Fine–Gray subdistribution hazard model revealed that the HR for PD development in the AS group was 1.82 (95%confidence interval [CI], 1.38–2.39, p < 0.001). A significant decrease in PD development was observed in patients with AS taking non-steroidal anti-inflammatory drugs (NSAIDs). The HR for atypical parkinsonism in the AS group was 3.86 (95%CI, 1.08–13.78, p < 0.05). Conclusion: We found that AS was associated with an increased risk of PD and atypical parkinsonism. NSAIDs used for AS control have some protective effects against PD. Further studies assessing whether biological treatment mitigates PD risk in patients with high activity are warranted.

Clinical and Genetic Analysis of Costa Rican Patients With Parkinson's Disease

Background: Most research in genomics of Parkinson's disease (PD) has been done in subjects of European ancestry, leading to sampling bias and leaving Latin American populations underrepresented. We sought to clinically characterize PD patients of Costa Rican origin and to sequence familial PD and atypical parkinsonism-associated genes in cases and controls.Methods: We enrolled 118 PD patients with 97 unrelated controls. Collected information included demographics, exposure to risk and protective factors, and motor and cognitive assessments. We sequenced coding and untranslated regions in familial PD and atypical parkinsonism-associated genes including GBA, SNCA, VPS35, LRRK2, GCH1, PRKN, PINK1, DJ-1, VPS13C, and ATP13A2.Results: Mean age of PD probands was 62.12 ± 13.51 years; 57.6% were male. The frequency of risk and protective factors averaged ~45%. Physical activity significantly correlated with better motor performance despite years of disease. Increased years of education were significantly associated with better cognitive function, whereas hallucinations, falls, mood disorders, and coffee consumption correlated with worse cognitive performance. We did not identify an association between tested genes and PD or any damaging homozygous or compound heterozygous variants. Rare variants in LRRK2 were nominally associated with PD; six were located between amino acids p.1620 and 1623 in the C-terminal-of-ROC (COR) domain of Lrrk2. Non-synonymous GBA variants (p.T369M, p.N370S, and p.L444P) were identified in three healthy individuals. One PD patient carried a pathogenic GCH1 variant, p.K224R.Discussion: This is the first study that describes sociodemographics, risk factors, clinical presentation, and genetics of Costa Rican patients with PD, adding information to genomics research in a Latino population.

Imaging features associated with idiopathic normal pressure hydrocephalus have high specificity even when comparing with vascular dementia and atypical parkinsonism

Background Vascular dementia (VaD) and atypical parkinsonism often present with symptoms that can resemble idiopathic normal pressure hydrocephalus (iNPH) and enlarged cerebral ventricles, and can be challenging differential diagnoses. The aim was to investigate frequencies of imaging features usually associated with iNPH and their radiological diagnostic accuracy in a sample containing the relevant differential diagnoses VaD, progressive supranuclear palsy (PSP), multiple system atrophy parkinsonian type (MSA-P), and healthy controls. Methods Nine morphological imaging features usually associated with iNPH were retrospectively investigated in MR images of 55 patients with shunt-responsive iNPH, 32 patients with VaD, 30 patients with PSP, 27 patients with MSA-P, and 39 age-matched healthy controls. Logistic regression and receiver operating characteristic curves were used to assess diagnostic accuracy, sensitivity, and specificity for each imaging finding. Results In a logistic regression model using iNPH diagnosis as a dependent variable, the following imaging features contributed significantly to the model: callosal angle (OR = 0.95 (0.92–0.99), p = 0.012), Evans’ index * 100 (OR = 1.51 (1.23–1.86), p < 0.001), enlarged Sylvian fissures (OR = 6.01 (1.42–25.40), p = 0.015), and focally enlarged sulci (OR = 10.18 (1.89–55.02), p = 0.007). Imaging features with 95% specificity for iNPH were: callosal angle ≤ 71°, temporal horns ≥ 7 mm, Evans’ index ≥ 0.37, iNPH Radscale ≥ 9, and presence of DESH, bilateral ventricular roof bulgings or focally enlarged sulci. A simplified version of the iNPH Radscale with only four features resulted in equally high diagnostic accuracy as the original iNPH Radscale. Conclusions There is a notable overlap between some of the commonly used imaging markers regarding iNPH, VaD and atypical parkinsonism, such as PSP. However, this study shows that the specificity of imaging markers usually associated with iNPH was high even when comparing with these challenging differential diagnoses. The callosal angle was the single imaging feature with highest diagnostic accuracy to discriminate iNPH from its mimics. A simplified rating scale using only a few selected features could be used with retained specificity.

The Genetic Landscape of Parkinsonism-Related Dystonias and Atypical Parkinsonism-Related Syndromes

In recent decades, genetic research has nominated promising pathways and biological insights contributing to the etiological landscape of parkinsonism-related dystonias and atypical parkinsonism-related syndromes. Several disease-causing mutations and genetic risk factors have been unraveled, providing a deeper molecular understanding of the complex genetic architecture underlying these conditions. These disorders are difficult to accurately diagnose and categorize, thus making genetics research challenging. On one hand, dystonia is an umbrella term linked to clinically heterogeneous forms of disease including dopa-responsive dystonia, myoclonus-dystonia, rapid-onset dystonia-parkinsonism and dystonia-parkinsonism, often viewed as a precursor to Parkinson’s disease. On the other hand, atypical parkinsonism disorders, such as progressive supranuclear palsy, multiple system atrophy and corticobasal degeneration, are rare in nature and represent a wide range of diverse and overlapping phenotypic variabilities, with genetic research limited by sample size availability. The current review summarizes the plethora of available genetic information for these diseases, outlining limits and future directions.