Genetic associations between Rapid Eye Movement (REM) sleep behavior disorder and cardiovascular diseases

BACKGROUND

Previous studies revealed that sleep disorders are potential risk factors for cardiovascular diseases, such as obstructive sleep apnea and rapid eye movement (REM) sleep behavior disorder (RBD). However, the causal associations between RBD and cardiovascular diseases remained unknown.

MATERIALS AND METHODS

We used the latest and largest summary-level genome-wide association studies of RBD, stroke and its subtypes, coronary artery disease (CAD), myocardial infarction (MI), and heart failure (HF) to select genetic variants as the instrumental variables. Mendelian randomization (MR) analysis was performed to test the causal associations between RBD and the cardiovascular diseases above. Inverse variance weighted method was used as the main analysis.

RESULTS

After multiple comparisons, genetically predicted RBD was significantly associated with the risk of HF [odds ratio (OR) = 1.033, 95% CI 1.013-1.052, p = 0.001]. Leave-one-out analysis further supported the robustness of the causal association. Furthermore, we identified a suggestive association between genetically predicted MI and RBD (OR = 0.716, 95% CI 0.546-0.940, p = 0.016). However, in our study no associations were identified of RBD with CAD or stroke and its subtypes.

CONCLUSION

Our study highlighted the potential associations between RBD and cardiovascular diseases at genetic level, including HF and MI. More studies were required to clarify the biological mechanisms involved the associations.

GBA1 rs3115534 Is Associated with REM Sleep Behavior Disorder in Parkinson's Disease in Nigerians

BACKGROUND

Rapid eye movement (REM) sleep behavior disorder (RBD) is an early feature of Parkinson's disease (PD) and dementia with Lewy bodies (DLB). Damaging coding variants in Glucocerebrosidase (GBA1) are a genetic risk factor for RBD. Recently, a population-specific non-coding risk variant (rs3115534) was found to be associated with PD risk and earlier onset in individuals of African ancestry.

OBJECTIVES

We aimed to investigate whether the GBA1 rs3115534 PD risk variant is associated with RBD in persons with PD.

METHODS

We studied 709 persons with PD and 776 neurologically healthy controls from Nigeria. All DNA samples were genotyped and imputed, and the GBA1 rs3115534 risk variant was extracted. The RBD screening questionnaire (RBDSQ) was used to assess symptoms of possible RBD.

RESULTS

RBD was present in 200 PD (28.2%) and 51 (6.6%) controls. We identified that the non-coding GBA1 rs3115534 risk variant is associated with possible RBD in individuals of Nigerian origin (β, 0.3640; standard error [SE], 0.103, P = 4.093e-04), as well as in all samples after adjusting for PD status (β, 0.2542; SE, 0.108; P = 0.019) suggesting that although non-coding, this variant may have the same downstream consequences as GBA1 coding variants.

CONCLUSIONS

Our results indicate that the non-coding GBA1 rs3115534 risk variant is associated with an increasing number of RBD symptoms in persons with PD of Nigerian origin. Further research is needed to assess if this variant is also associated with polysomnography-defined RBD and with RBD symptoms in DLB. © 2024 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Mitochondrial DNA deletions in the cerebrospinal fluid of patients with idiopathic REM sleep behaviour disorder

BACKGROUND

Idiopathic rapid eye movement (REM) sleep behaviour disorder (IRBD) represents the prodromal stage of Lewy body disorders (Parkinson's disease (PD) and dementia with Lewy bodies (DLB)) which are linked to variations in circulating cell-free mitochondrial DNA (cf-mtDNA). Here, we assessed whether altered cf-mtDNA release and integrity are already present in IRBD.

METHODS

We used multiplex digital PCR (dPCR) to quantify cf-mtDNA copies and deletion ratio in cerebrospinal fluid (CSF) and serum in a cohort of 71 participants, including 1) 17 patients with IRBD who remained disease-free (non-converters), 2) 34 patients initially diagnosed with IRBD who later developed either PD or DLB (converters), and 3) 20 age-matched controls without IRBD or Parkinsonism. In addition, we investigated whether CD9-positive extracellular vesicles (CD9-EVs) from CSF and serum samples contained cf-mtDNA.

FINDINGS

Patients with IRBD, both converters and non-converters, exhibited more cf-mtDNA with deletions in the CSF than controls. This finding was confirmed in CD9-EVs. The high levels of deleted cf-mtDNA in CSF corresponded to a significant decrease in cf-mtDNA copies in CD9-EVs in both IRBD non-converters and converters. Conversely, a significant increase in cf-mtDNA copies was found in serum and CD9-EVs from the serum of patients with IRBD who later converted to a Lewy body disorder.

INTERPRETATION

Alterations in cf-mtDNA copy number and deletion ratio known to occur in Lewy body disorders are already present in IRBD and are not a consequence of Lewy body disease conversion. This suggests that mtDNA dysfunction is a primary molecular mechanism of the pathophysiological cascade that precedes the full clinical motor and cognitive manifestation of Lewy body disorders.

FUNDING

Funded by Michael J. Fox Foundation research grant MJFF-001111. Funded by MICIU/AEI/10.13039/501100011033 "ERDF A way of making Europe", grants PID2020-115091RB-I00 (RT) and PID2022-143279OB-I00 (ACo). Funded by Instituto de Salud Carlos III and European Union NextGenerationEU/PRTR, grant PMP22/00100 (RT and ACo). Funded by AGAUR/Generalitat de Catalunya, grant SGR00490 (RT and ACo). MP has an FPI fellowship, PRE2018-083297, funded by MICIU/AEI/10.13039/501100011033 "ESF Investing in your future".

HLA in isolated REM sleep behavior disorder and Lewy body dementia

Synucleinopathies-related disorders such as Lewy body dementia (LBD) and isolated/idiopathic REM sleep behavior disorder (iRBD) have been associated with neuroinflammation. In this study, we examined whether the human leukocyte antigen (HLA) locus plays a role in iRBD and LBD. In iRBD, HLA-DRB1*11:01 was the only allele passing FDR correction (OR = 1.57, 95% CI = 1.27-1.93, p = 2.70e-05). We also discovered associations between iRBD and HLA-DRB1 70D (OR = 1.26, 95%CI = 1.12-1.41, p = 8.76e-05), 70Q (OR = 0.81, 95%CI = 0.72-0.91, p = 3.65e-04) and 71R (OR = 1.21, 95%CI = 1.08-1.35, p = 1.35e-03). Position 71 (pomnibus  = 0.00102) and 70 (pomnibus  = 0.00125) were associated with iRBD. Our results suggest that the HLA locus may have different roles across synucleinopathies.

Mitochondrial function-associated genes underlie cortical atrophy in prodromal synucleinopathies

Isolated rapid eye movement sleep behaviour disorder (iRBD) is a sleep disorder characterized by the loss of rapid eye movement sleep muscle atonia and the appearance of abnormal movements and vocalizations during rapid eye movement sleep. It is a strong marker of incipient synucleinopathy such as dementia with Lewy bodies and Parkinson's disease. Patients with iRBD already show brain changes that are reminiscent of manifest synucleinopathies including brain atrophy. However, the mechanisms underlying the development of this atrophy remain poorly understood. In this study, we performed cutting-edge imaging transcriptomics and comprehensive spatial mapping analyses in a multicentric cohort of 171 polysomnography-confirmed iRBD patients [67.7 ± 6.6 (49-87) years; 83% men] and 238 healthy controls [66.6 ± 7.9 (41-88) years; 77% men] with T1-weighted MRI to investigate the gene expression and connectivity patterns associated with changes in cortical thickness and surface area in iRBD. Partial least squares regression was performed to identify the gene expression patterns underlying cortical changes in iRBD. Gene set enrichment analysis and virtual histology were then done to assess the biological processes, cellular components, human disease gene terms, and cell types enriched in these gene expression patterns. We then used structural and functional neighbourhood analyses to assess whether the atrophy patterns in iRBD were constrained by the brain's structural and functional connectome. Moreover, we used comprehensive spatial mapping analyses to assess the specific neurotransmitter systems, functional networks, cytoarchitectonic classes, and cognitive brain systems associated with cortical changes in iRBD. All comparisons were tested against null models that preserved spatial autocorrelation between brain regions and compared to Alzheimer's disease to assess the specificity of findings to synucleinopathies. We found that genes involved in mitochondrial function and macroautophagy were the strongest contributors to the cortical thinning occurring in iRBD. Moreover, we demonstrated that cortical thinning was constrained by the brain's structural and functional connectome and that it mapped onto specific networks involved in motor and planning functions. In contrast with cortical thickness, changes in cortical surface area were related to distinct genes, namely genes involved in the inflammatory response, and to different spatial mapping patterns. The gene expression and connectivity patterns associated with iRBD were all distinct from those observed in Alzheimer's disease. In summary, this study demonstrates that the development of brain atrophy in synucleinopathies is constrained by specific genes and networks.

Genome-wide association study of REM sleep behavior disorder identifies polygenic risk and brain expression effects

Rapid-eye movement (REM) sleep behavior disorder (RBD), enactment of dreams during REM sleep, is an early clinical symptom of alpha-synucleinopathies and defines a more severe subtype. The genetic background of RBD and its underlying mechanisms are not well understood. Here, we perform a genome-wide association study of RBD, identifying five RBD risk loci near SNCA, GBA, TMEM175, INPP5F, and SCARB2. Expression analyses highlight SNCA-AS1 and potentially SCARB2 differential expression in different brain regions in RBD, with SNCA-AS1 further supported by colocalization analyses. Polygenic risk score, pathway analysis, and genetic correlations provide further insights into RBD genetics, highlighting RBD as a unique alpha-synucleinopathy subpopulation that will allow future early intervention.

Striatal-Inoculation of α-Synuclein Preformed Fibrils Aggravated the Phenotypes of REM Sleep without Atonia in A53T BAC-SNCA Transgenic Mice

Accumulation of α-synuclein (α-syn) is the pathological hallmark of α-synucleinopathy. Rapid eye movement (REM) sleep behavior disorder (RBD) is a pivotal manifestation of α-synucleinopathy including Parkinson's disease (PD). RBD is clinically confirmed by REM sleep without atonia (RWA) in polysomnography. To accurately characterize RWA preceding RBD and their underlying α-syn pathology, we inoculated α-syn preformed fibrils (PFFs) into the striatum of A53T human α-syn BAC transgenic (A53T BAC-SNCA Tg) mice which exhibit RBD-like phenotypes with RWA. RWA phenotypes were aggravated by PFFs-inoculation in A53T BAC-SNCA Tg mice at 1 month after inoculation, in which prominent α-syn pathology in the pedunculopontine nucleus (PPN) was observed. The intensity of RWA phenotype could be dependent on the severity of the underlying α-syn pathology.

Serum MicroRNAs Predict Isolated Rapid Eye Movement Sleep Behavior Disorder and Lewy Body Diseases

BACKGROUND

Isolated rapid eye movement sleep behavior disorder (IRBD) is a well-established clinical risk factor for Lewy body diseases (LBDs), such as Parkinson's disease (PD) and dementia with Lewy bodies (DLB).

OBJECTIVE

To elucidate whether serum microRNA (miRNA) deregulation in IRBD can antedate the diagnosis of LBD by performing a longitudinal study in different progression stages of IRBD before and after LBD diagnosis and assessing the predictive performance of differentially expressed miRNAs by machine learning-based modeling.

METHODS

Using genome-wide miRNA analysis and real-time quantitative polymerase chain reaction validation, we assessed serum miRNA profiles from patients with IRBD stratified by dopamine transporter (DaT) single-photon emission computed tomography into DaT-negative IRBD (n = 17) and DaT-positive IRBD (n = 21), IRBD phenoconverted into LBD (n = 13), and controls (n = 20). Longitudinally, we followed up the IRBD cohort by studying three time point serum samples over 26 months.

RESULTS

We found sustained cross-sectional and longitudinal deregulation of 12 miRNAs across the RBD continuum, including DaT-negative IRBD, DaT-positive IRBD, and LBD phenoconverted IRBD (let-7c-5p, miR-19b-3p, miR-140, miR-22-3p, miR-221-3p, miR-24-3p, miR-25-3p, miR-29c-3p, miR-361-5p, miR-425-5p, miR-4505, and miR-451a) (false discovery rate P < 0.05). Age- and sex-adjusted predictive modeling based on the 12 differentially expressed miRNA biosignatures discriminated IRBD and PD or DLB from controls with an area under the curve of 98% (95% confidence interval: 89-99%).

CONCLUSIONS

Besides clinical diagnosis of IRBD or imaging markers such as DaT single-photon emission computed tomography, specific miRNA biosignatures alone hold promise as progression biomarkers for patients with IRBD for predicting PD and DLB clinical outcomes. Further miRNA studies in other PD at-risk populations, such as LRRK2 mutation asymptomatic carriers or hyposmic subjects, are warranted. © 2022 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Novel Associations of BST1 and LAMP3 With REM Sleep Behavior Disorder

OBJECTIVE

To examine the role of genes identified through genome-wide association studies (GWASs) of Parkinson disease (PD) in the risk of isolated REM sleep behavior disorder (iRBD).

METHODS

We fully sequenced 25 genes previously identified in GWASs of PD in a total of 1,039 patients with iRBD and 1,852 controls. The role of rare heterozygous variants in these genes was examined with burden tests. The contribution of biallelic variants was further tested. To examine the potential effect of rare nonsynonymous BST1 variants on the protein structure, we performed in silico structural analysis. Finally, we examined the association of common variants using logistic regression adjusted for age and sex.

RESULTS

We found an association between rare heterozygous nonsynonymous variants in BST1 and iRBD (p = 0.0003 at coverage >50× and 0.0004 at >30×), driven mainly by 3 nonsynonymous variants (p.V85M, p.I101V, and p.V272M) found in 22 (1.2%) controls vs 2 (0.2%) patients. All 3 variants seem to be loss-of-function variants with a potential effect on the protein structure and stability. Rare noncoding heterozygous variants in LAMP3 were also associated with iRBD (p = 0.0006 at >30×). We found no association between rare heterozygous variants in the rest of genes and iRBD. Several carriers of biallelic variants were identified, yet there was no overrepresentation in iRBD.

CONCLUSION

Our results suggest that rare coding variants in BST1 and rare noncoding variants in LAMP3 are associated with iRBD. Additional studies are required to replicate these results and to examine whether loss of function of BST1 could be a therapeutic target.

Unexpected Finding of Idiopathic REM Sleep Behavior Disorder in a Young Healthy Male With Snoring: A Case Report

None

Idiopathic rapid eye movement sleep behavior disorder is characterized by vocalizations and complex motor behaviors during sleep. We report a case of a 44-year-old male with a 20-year history of dream enactment behavior that was incidentally captured on a polysomnogram during an evaluation for obstructive sleep apnea. Genetic testing found the patient had a homozygous deletion for one of the five tandem repeats in exon 18 of the PER3 gene. This case highlights a potential genetic basis for idiopathic rapid eye movement sleep behavior disorder.

CITATION

Brock MS, Shirley S, Rohena L, Moore BA, Mysliwiec V. Unexpected finding of idiopathic REM sleep behavior disorder in a young healthy male with snoring: a case report. J Clin Sleep Med. 2019;15(9):1369-1371.

Circadian rhythms of melatonin and peripheral clock gene expression in idiopathic REM sleep behavior disorder

OBJECTIVE

To evaluate changes in the expression of clock genes and melatonin levels in patients with idiopathic REM sleep behavior disorder (RBD) as a potential early stage of synucleinopathies.

METHODS

We assessed the rhythmicity of circadian clock genes using real time-quantitative polymerase chain reaction and 24-h blood melatonin profiles using radio-immunoassay in 10 RBD patients and nine age-matched controls.

RESULTS

The RBD patients did not show circadian rhythmicity for clock genes Per2, Bmal1, and Nr1d1 but the rhythmicity of Per 1 remained, and the amplitude of Per3 was diminished. The 24-h melatonin rhythm did not differ between RBD patients and healthy control subjects. Melatonin profile in RBD patients was delayed by 2 h compared to controls, the habitual sleep phases were phase delayed by about 1 h, however no phase shift occurred in any of the clock genes studied. The control group had stable acrophases of melatonin rhythms of approximately 5 h whereas the RBD patients had a more dispersed range over 11 h.

CONCLUSIONS

Our results suggest that RBD could be associated with altered expression of clock genes and delayed melatonin secretion. Thus, we argue that circadian system dysregulation could play a role in RBD.

Relationships between Rapid Eye Movement Sleep Behavior Disorder and Neurodegenerative Diseases: Clinical Assessments, Biomarkers, and Treatment

OBJECTIVE

Rapid eye movement sleep behavior disorder (RBD) is characterized by dream enactment and loss of muscle atonia during rapid eye movement sleep. RBD is closely related to α-synucleinopathies including Parkinson's disease, dementia with Lewy bodies, and multiple system atrophy. Many studies have investigated the markers of imaging and neurophysiological, genetic, cognitive, autonomic function of RBD and their predictive value for neurodegenerative diseases. This report reviewed the progress of these studies and discussed their limitations and future research directions.

DATA SOURCES

Using the combined keywords: "RBD", "neurodegenerative disease", "Parkinson disease", and "magnetic resonance imaging", the PubMed/MEDLINE literature search was conducted up to January 1, 2018.

STUDY SELECTION

A total of 150 published articles were initially identified citations. Of the 150 articles, 92 articles were selected after further detailed review. This study referred to all the important English literature in full.

RESULTS

Single-nucleotide polymorphisms in SCARB2 (rs6812193) and MAPT (rs12185268) were significantly associated with RBD. The olfactory loss, autonomic dysfunction, marked electroencephalogram slowing during both wakefulness and rapid eye movement sleep, and cognitive impairments were potential predictive markers for RBD conversion to neurodegenerative diseases. Traditional structural imaging studies reported relatively inconsistent results, whereas reduced functional connectivity between the left putamen and substantia nigra and dopamine transporter uptake demonstrated by functional imaging techniques were relatively consistent findings.

CONCLUSIONS

More longitudinal studies should be conducted to evaluate the predictive value of biomarkers of RBD. Moreover, because the glucose and dopamine metabolisms are not specific for assessing cognitive cognition, the molecular metabolism directly related to cognition should be investigated. There is a need for more treatment trials to determine the effectiveness of interventions of RBD on preventing the conversion to neurodegenerative diseases.

The dementia-associated APOE ε4 allele is not associated with rapid eye movement sleep behavior disorder

The present study aimed to examine whether the APOE ε4 allele, associated with dementia with Lewy bodies (DLB), and possibly with dementia in Parkinson's disease (PD), is also associated with idiopathic rapid eye movement sleep behavior disorder (RBD). Two single nucleotide polymorphisms, rs429358 and rs7412, were genotyped in RBD patients (n = 480) and in controls (n = 823). APOE ε4 allele frequency was 0.14 among RBD patients and 0.13 among controls (OR = 1.11, 95% CI: 0.88-1.40, p = 0.41). APOE ε4 allele frequencies were similar in those who converted to DLB (0.14) and those who converted to Parkinson's disease (0.12) or multiple system atrophy (0.14, p = 1.0). The APOE ε4 allele is neither a risk factor for RBD nor it is associated with conversion from RBD to DLB or other synucleinopathies.

Sleep Disorders in Parkinsonian and Nonparkinsonian LRRK2 Mutation Carriers

Objective

In idiopathic Parkinson disease (IPD) sleep disorders are common and may antedate the onset of parkinsonism. Based on the clinical similarities between IPD and Parkinson disease associated with LRRK2 gene mutations (LRRK2-PD), we aimed to characterize sleep in parkinsonian and nonmanifesting LRRK2 mutation carriers (NMC).

Methods

A comprehensive interview conducted by sleep specialists, validated sleep scales and questionnaires, and video-polysomnography followed by multiple sleep latency test (MSLT) assessed sleep in 18 LRRK2-PD (17 carrying G2019S and one R1441G mutations), 17 NMC (11 G2019S, three R1441G, three R1441C), 14 non-manifesting non-carriers (NMNC) and 19 unrelated IPD.

Results

Sleep complaints were frequent in LRRK2-PD patients; 78% reported poor sleep quality, 33% sleep onset insomnia, 56% sleep fragmentation and 39% early awakening. Sleep onset insomnia correlated with depressive symptoms and poor sleep quality. In LRRK2-PD, excessive daytime sleepiness (EDS) was a complaint in 33% patients and short sleep latencies on the MSLT, which are indicative of objective EDS, were found in 71%. Sleep attacks occurred in three LRRK2-PD patients and a narcoleptic phenotype was not observed. REM sleep behavior disorder (RBD) was diagnosed in three LRRK2-PD. EDS and RBD were always reported to start after the onset of parkinsonism in LRRK2-PD. In NMC, EDS was rarely reported and RBD was absent. When compared to IPD, sleep onset insomnia was more significantly frequent, EDS was similar, and RBD was less significantly frequent and less severe in LRRK2-PD. In NMC, RBD was not detected and sleep complaints were much less frequent than in LRRK2-PD. No differences were observed in sleep between NMC and NMNC.

Conclusions

Sleep complaints are frequent in LRRK2-PDand show a pattern that when compared to IPD is characterized by more frequent sleep onset insomnia, similar EDS and less prominent RBD. Unlike in IPD, RBD and EDS seem to be not markers of the prodromal stage of LRRK2-PD.

Parkinson's Disease Genetic Loci in Rapid Eye Movement Sleep Behavior Disorder

Rapid eye movement (REM) sleep behavior disorder (RBD) is a prodromal condition for Parkinson's disease (PD) and other synucleinopathies, which often occurs many years before the onset of PD. We analyzed 261 RBD patients and 379 controls for nine PD-associated SNPs and examined their effects, first upon on RBD risk and second, on eventual progression to synucleinopathies in a prospective follow-up in a subset of patients. The SCARB2 rs6812193 (OR = 0.67, 95 % CI = 0.51-0.88, p = 0.004) and the MAPT rs12185268 (OR-0.43, 95 % CI-0.26-0.72, p = 0.001) were associated with RBD in different models. Kaplan-Meier survival analysis in a subset of RBD patients (n = 56), demonstrated that homozygous carriers of the USP25 rs2823357 SNP had progressed to synucleinopathies faster than others (log-rank p = 0.003, Breslow p = 0.005, Tarone-Ware p = 0.004). As a proof-of-concept study, these results suggest that RBD may be associated with at least a subset of PD-associated genes, and demonstrate that combining genetic and prodromal clinical data may help identifying individuals that are either more or less susceptible to develop synucleinopathies. More studies are necessary to replicate these results, and identify more genetic factors affecting progression from RBD to synucleinopathies.

Absence of rapid eye movement sleep behavior disorder in 11 members of the pallidopontonigral degeneration kindred

BACKGROUND

Rapid eye movement sleep behavior disorder (RBD) is a parasomnia that is manifested by dream enactment behavior. The electrophysiologic substrate for RBD on polysomnography is rapid eye movement sleep without atonia. Rapid eye movement sleep behavior disorder likely stems from neuronal network dysfunction in the brainstem, although it is not yet clear which specific networks are involved. Rapid eye movement sleep behavior disorder is often associated with the sporadic synucleinopathies but rarely associated with the sporadic tauopathies. There are no reports on the possible association of rapid eye movement sleep without atonia and RBD with any familial tauopathy.

OBJECTIVE

To characterize the clinical sleep and polysomnography features in a kindred with a familial tauopathy.

METHODS

We performed standard polysomnography in 11 members of the pallidopontonigral degeneration kindred irrespective of any sleep-related complaints. Neuropathologic findings were analyzed in those who subsequently underwent autopsy.

RESULTS

Six affected and 5 genealogically at-risk family members were studied. None of the 11 had a history of dream enactment behavior. Nine of the 11 members attained sufficient rapid eye movement sleep on polysomnography, and the electrophysiologic features of rapid eye movement sleep without atonia and behavioral manifestations of RBD were absent in all subjects. Neuropathologic examination of 4 affected individuals revealed marked nigral degeneration in 3 along with mild degenerative changes in the locus coeruleus, pontine nuclei and tegmentum, and medullary tegmentum.

CONCLUSIONS

These findings argue against nigral degeneration being the primary cause of RBD. The absence of the historical, electrophysiologic, and behavioral manifestations of RBD in this kindred provides further evidence that RBD is rare in the sporadic and familial tauopathies. The difference in frequencies of RBD associated with the synucleinopathies compared with the tauopathies suggests differences in the selective vulnerability of brainstem circuits between the synucleinopathies and tauopathies.

Non-movement disorder heralds symptoms of Machado-Joseph disease years before ataxia

We describe three patients with the Machado-Joseph disease (MJD) genetic abnormality who had non-movement disorder neurological symptoms or signs that preceded the gait ataxia by several years. This implies that some clinical manifestations other than ataxia may be considered part of the herald symptoms of MJD, especially in the setting of a positive family history.

Rapid eye movement sleep behavior disorder in parkinsonism with parkin mutations

Rapid eye movement sleep behavior disorder (RBD) in the setting of parkinsonism or dementia often reflects an underlying synucleinopathy. Lewy bodies, intraneuronal aggregates containing abnormal alpha-synuclein, are absent in most cases of parkinsonism with parkin mutations (Park2). We performed clinical history and video-polysomnography in 10 Park2 patients (seven men; age, 51.2 +/- 11.6 years; parkinsonism duration, 18.3 +/- 11.2 years) and found RBD in 6. In all instances, RBD followed the onset of motor symptoms by several years. Our study shows that RBD is frequent in Park2, suggesting that mechanisms other than synuclein deposition can cause RBD in neurodegenerative disorders.

Neural melanocortin receptors are differentially expressed and regulated by stress in rat hypothalamic-pituitary-adrenal axis

Genetic knockout and null mutations of melanocortin system components lead to phenotypes that recapitulate the metabolic syndrome such as obesity, hypertension and insulin resistance. Since stress is known to modify metabolic and cardiovascular function, we hypothesized the involvement of the neural melanocortin system in the stress response. Male rats were subjected to rapid-eye-movement sleep deprivation stress and the levels of proopiomelanocortin (POMC), MC3R, MC4R and MC5R transcripts in the hypothalamic-pituitary-adrenal axis (HPA) determined by real-time PCR. Increased levels of POMC transcripts were observed in the hypothalamus and adrenal gland tissues but there were no significant changes in the expression of the receptors genes. Whereas MC3R and MC5R are expressed in all HPA tissues, MC4R seems to be restricted mainly to the hypothalamus. It is possible that melanocortin receptors function in different aspects of the neuron. In vitro studies showed similar cellular distribution patterns for MC3R and MC4R and sequence analyses revealed strong conservation of the putative G-protein coupled receptors (GPCR) C-terminal membrane localization signal, EX(3-7)II/L motif, in MC3R, MC4R and MC5R. These data suggest that the physiological roles of neural melanocortin receptors, MC3R and MC4R, are likely determined by distinct tissue distribution patterns and suggest a role for hypothalamic and intra-adrenal melanocortin systems in the manifestation of stress related pathologies.

HLA typing does not predict REM sleep behaviour disorder and hallucinations in Parkinson's disease

HLA-DR2 haplotype and DQ1 DNA alleles, characterizing 90 to 100% of all narcoleptic patients, were found to be equally distributed in 20 Parkinson's disease (PD) patients with early hallucinations, rapid eye movement (REM) sleep-related behaviour disturbances (RBD), and sleep onset in REM (SOREM), and in 20 PD patients without hallucinations, despite 10 to 15 years of treatment, and no RBD or SOREM.

Presumed rapid eye movement behavior disorder in Machado-Joseph disease (spinocerebellar ataxia type 3)

Rapid eye movement behavior disorder (RBD) is a recently recognized sleep disorder in which patients are occasionally not paralyzed during the dream portions of sleep. When not idiopathic, this state has been associated primarily with parkinsonian conditions but also with a small number of medications and other neurodegenerative disorders. Dopamine deficiency may play a role in some patients. This report describes the occurrence of a syndrome that appears to be RBD in 6 of 7 patients followed with Spinocerebellar ataxia type 3 (Machado-Joseph disease). Polysomnography was normal in 1 patient. Two of these patients had had single photon emission computed tomographic imaging of the dopamine transporter 1 year previously.