Serum miR-96-5P and miR-339-5P Are Potential Biomarkers for Multiple System Atrophy and Parkinson's Disease.

Parkinson's disease (PD) and Multiple System Atrophy (MSA) are progressive neurodegenerative diseases with overlap of symptoms in early stages of disease. No reliable biomarker exists and the diagnosis is mainly based on clinical features. Several studies suggest that miRNAs are involved in PD and MSA pathogenesis. Our goal was to study two serum circulating microRNAs (miR-96-5p and miR-339-5p) as novel biomarkers for the differential diagnosis between PD and MSA. Serum samples were obtained from 51 PD patients, 52 MSA patients and 56 healthy controls (HC). We measured levels of miRNAs using quantitative PCR and compared the levels of miR-96-5p and miR-339-5p among PD, MSA and HC groups using a one-way analysis of variance. Correlations between miRNA expression and clinical data were calculated using Pearson's rho test. We used the miRTarBase to detect miRNA targets and STRING to evaluate co-expression relationship among target genes. MiR-96-5p was significantly increased in MSA patients compared with HC (Fold change (fc): 3.6; p = 0.0001) while it was decreased in PD patients compared with HC (Fold change: 4; p = 0.0002). Higher miR-96-5P levels were directly related to longer disease duration in MSA patients. We observed a significant increase of miR-339-5p in MSA patients compared with PD patients (fc: 2.5; p = 0.00013). miR-339-5p was increased in MSA patients compared with HC (fc: 2.4; p = 0.002). We identified 32 target genes of miR-96-5p and miR-339-5p, some of which are involved in neurodegenerative diseases. The study of those miRNAs could be useful to identify non-invasive biomarkers for early differential diagnosis between PD and MSA.

Genetic characterization of a cohort with familial parkinsonism and cognitive-behavioral syndrome: A Next Generation Sequencing study.

OBJECTIVE: To perform the genetic characterization of a cohort with familial parkinsonism and cognitive-behavioral syndrome. METHODS: A Next Generation Sequencing - based targeted sequencing of 32 genes associated to various neurodegenerative phenotypes, plus a screening for SNCA Copy Number Variations and C9orf72 repeat expansion, was applied in a cohort of 85 Italian patients presenting with parkinsonism and cognitive and/or behavioral syndrome and a positive familial history for any neurodegenerative disorder (i.e., dementia, movement disorders, amyotrophic lateral sclerosis). RESULTS: Through this combined genetic approach, we detected potentially relevant genetic variants in 25.8% of patients with familial parkinsonism and cognitive and/or behavioral syndrome. Peculiar phenotypes are described (Cortico-basal syndrome with APP, Posterior Cortical Atrophy with GBA, Progressive Supranuclear Palsy-like with GRN, Multiple System Atrophy with TARDBP). The majority of patients presented a rigid-bradykinetic parkinsonian syndrome, while rest tremor was less common. Myoclonic jerks, pyramidal signs, dystonic postures and vertical gaze disturbances were more frequently associated with the presence of a pathogenic variant in one of the tested genes. CONCLUSIONS: Given the syndromic approach adopted in our study, we were able to provide a detailed clinical description of patients beyond the boundaries of specific clinical diagnoses and describe peculiar phenotypes. This observation further supports the knowledge that genetic disorders present phenotypic overlaps across different neurodegenerative syndromes, highlighting the limitations of current clinical diagnostic criteria defining sharp boundaries between distinct conditions.

The role of sensory and olfactory pathways in multiple chemical sensitivity.

Multiple chemical sensitivity (MCS) is characterised by non-specific and recurring symptoms affecting multiple organs and associated with exposure to chemicals, even at low concentrations, which are, under normal circumstances, harmless to the general population. Symptoms include general discomfort, cardiovascular instability, irritation of the sensory organs, breath disorders, hypersensitivity affecting the skin and epithelial lining of the gut, throat and lungs, anxiety, and learning and memory loss. Chemical intolerance is a key distinguishing feature of MCS, limiting considerably patients' lifestyle with serious social, occupational and economic implications. Since no specific diagnostic markers are currently available for chemical intolerance, the diagnosis relies on clinical symptoms. Despite the formulation of several hypotheses regarding the pathophysiology of MCS, its mechanisms remain undefined. A person-centred care approach, based on multidisciplinary and individualised medical plans, has shown promising results. However, more definite treatment strategies are required. We have reviewed the main experimental studies on MCS pathophysiology, focusing on the brain networks involved, the impact of environmental pollution on the olfactory system and the correlation with other pathologies such as neurodegenerative diseases. Finally, we discuss treatment strategies targeting the olfactory system.

GBA-Related Parkinson's Disease: Dissection of Genotype-Phenotype Correlates in a Large Italian Cohort.

BACKGROUND: Variants in GBA are the most common genetic risk factor for Parkinson's disease (PD). The impact of different variants on the PD clinical spectrum is still unclear. OBJECTIVES: We determined the frequency of GBA-related PD in Italy and correlated GBA variants with motor and nonmotor features and their occurrence over time. METHODS: Sanger sequencing of the whole GBA gene was performed. Variants were classified as mild, severe, complex, and risk. ß-glucocerebrosidase activity was measured. The Kaplan-Meier method and Cox proportional hazard regression models were performed. RESULTS: Among 874 patients with PD, 36 variants were detected in 14.3%, including 20.4% early onset. Patients with GBA-PD had earlier and more frequent occurrence of several nonmotor symptoms. Patients with severe and complex GBA-PD had the highest burden of symptoms and a higher risk of hallucinations and cognitive impairment. Complex GBA-PD had the lowest ß-glucocerebrosidase activity. CONCLUSIONS: GBA-PD is highly prevalent in Italy. Different types of mutations underlie distinct phenotypic profiles. © 2020 International Parkinson and Movement Disorder Society.

Cerebrolysin improves peripheral inflammatory pain: Sex differences in two models of acute and chronic mechanical hypersensitivity.

Chronic inflammatory pain is a major health problem worldwide with high prevalence in women. Cerebrolysin is a multimodal neuropeptide preparation that crosses the blood brain barrier and displays neuroprotective properties in aging and disease. Previously, we showed that cerebrolysin reduced mechanical allodynia in a model of persistent inflammation and pain. We aim to build upon the findings of our previous study by investigating the response to acute administration of cerebrolysin in two models of peripheral inflammation and assessing sex differences. We utilized the complete Freund's adjuvant (CFA) that produces maximal oedema and mechanical allodynia within days and carrageenan that produces similar effects within hours. Cerebrolysin reversed the mechanical allodynia in both sexes in CFA-treated rats. On the other hand, in rats treated with carrageenan, cerebrolysin was only effective in reducing mechanical allodynia in female rats. In conclusion, the present study shows that cerebrolysin effects may be sex-specific depending on different mechanisms that are at play in these two models of peripheral inflammatory pain. Further investigations are required to determine the factors contributing to sex differences.

Serum miR-30c-5p is a potential biomarker for multiple system atrophy.

Multiple system atrophy (MSA) is a neurodegenerative disease that belongs to the α synucleinopathies. Clinically, there is an overlap between MSA and Parkinson's disease (PD), especially at the early disease stage. However, these two pathologies differ in terms of disease progression. Currently, no biomarker exists to differentiate MSA from PD. MicroRNAs are non-coding RNAs implicated in gene expression regulation. MiRNAs modulate cellular activity and they control a range of physiological and pathological functions. miRNAs are found in biofluids, such as blood, serum, plasma, saliva, and cerebrospinal fluid. Many groups, including ours, found that circulating miRNAs are differently expressed in blood, plasma, serum and cerebrospinal fluid of PD and MSA patients. In the present study, our primary aim was to determine if serum mir-30-5p and mir-148b-5p can be used as biomarkers for early diagnosis of PD and/or MSA. Our secondary goal was to determine if serum levels of those miRNAs can be correlated with the patients' clinical profile. Using quantitative PCR (qPCR), we evaluated expression levels of miR-30c-5p and miR148b-5p in serum samples from PD (n = 56), MSA (n = 49), and healthy control (n = 50) subjects. We have found that miR-30c-5p is significantly upregulated in MSA if compared with PD and healthy control subjects. Moreover, serum miR-30c-5p levels correlate with disease duration in both MSA and PD. No significant difference was found in miR-148b-5p among MSA, PD and healthy control subjects. Our results suggest a possible role of serum miR-30-5p as a biomarker for diagnosis and progression of MSA.

Role of proteoglycans and glycosaminoglycans in Duchenne muscular dystrophy.

Duchenne muscular dystrophy (DMD) is an inherited fatal X-linked myogenic disorder with a prevalence of 1 in 3500 male live births. It affects voluntary muscles, and heart and breathing muscles. DMD is characterized by continuous degeneration and regeneration cycles resulting in extensive fibrosis and a progressive reduction in muscle mass. Since the identification of a reduction in dystrophin protein as the cause of this disorder, numerous innovative and experimental therapies, focusing on increasing the levels of dystrophin, have been proposed, but the clinical improvement has been unsatisfactory. Dystrophin forms the dystrophin-associated glycoprotein complex and its proteins have been studied as a promising novel therapeutic target to treat DMD. Among these proteins, cell surface glycosaminoglycans (GAGs) are found almost ubiquitously on the surface and in the extracellular matrix (ECM) of mammalian cells. These macromolecules interact with numerous ligands, including ECM constituents, adhesion molecules and growth factors that play a crucial role in muscle development and maintenance. In this article, we have reviewed in vitro, in vivo and clinical studies focused on the functional role of GAGs in the pathophysiology of DMD with the final aim of summarizing the state of the art of GAG dysregulation within the ECM in DMD and discussing future therapeutic perspectives.

Mitochondrial dysfunction in fibroblasts of Multiple System Atrophy.

Multiple System Atrophy is a severe neurodegenerative disorder which is characterized by a variable clinical presentation and a broad neuropathological spectrum. The pathogenic mechanisms are almost completely unknown. In the present study, we established a cellular model of MSA by using fibroblasts' primary cultures and performed several experiments to investigate the causative mechanisms of the disease, with a particular focus on mitochondrial functioning. Fibroblasts' analyses (7 MSA-P, 7 MSA-C and 6 healthy controls) displayed several anomalies in patients: an impairment of respiratory chain activity, in particular for succinate Coenzyme Q reductase (p < 0.05), and a reduction of complex II steady-state level (p < 0.01); a reduction of Coenzyme Q10 level (p < 0.001) and an up-regulation of some CoQ10 biosynthesis enzymes, namely COQ5 and COQ7; an impairment of mitophagy, demonstrated by a decreased reduction of mitochondrial markers after mitochondrial inner membrane depolarization (p < 0.05); a reduced basal autophagic activity, shown by a decreased level of LC3 II (p < 0.05); an increased mitochondrial mass in MSA-C, demonstrated by higher TOMM20 levels (p < 0.05) and suggested by a wide analysis of mitochondrial DNA content in blood of large cohorts of patients. The present study contributes to understand the causative mechanisms of Multiple System Atrophy. In particular, the observed impairment of respiratory chain activity, mitophagy and Coenzyme Q10 biosynthesis suggests that mitochondrial dysfunction plays a crucial role in the pathogenesis of the disease. Furthermore, these findings will hopefully contribute to identify novel therapeutic targets for this still incurable disorder.

Physical rehabilitation modulates microRNAs involved in multiple sclerosis: a case report.

This study shows that neuromuscular taping improves gait, balance, pain and ability to walk and conduct daily activities in a multiple sclerosis patient. It is the first study to identify a panel of miRNAs modulated throughout rehabilitation using neuromuscular taping in a multiple sclerosis patient.

ApoE ε4 Allele Related Alterations in Hippocampal Connectivity in Early Alzheimer's Disease Support Memory Performance.

BACKGROUND: Whether the presence of the Apolipoprotein E ε4 allele modulates hippocampal connectivity networks in abnormal ageing has yet to be fully clarified. OBJECTIVE: Allele-dependent differences in this pattern of functional connectivity were investigated in patients with very mild neurodegeneration of the Alzheimer's type, carriers and non-carriers of the ε4 allele. METHOD: A seed-based connectivity approach was used. The two groups were similar in demographics, volumetric measures of brain structure, and cognitive profiles. RESULTS: ε4-carriers had increased connectivity between the seed area in the left hippocampus and 1) a left insular/lateral prefrontal region and 2) the contralateral right parietal cortex. Moreover, hippocampus- to-parietal connectivity in the group of ε4 carriers was positively associated with memory performance, indicating that the between-group difference reflects compensatory processes. Retrospective analyses of functional connectivity based on patients from the ADNI initiative confirmed this pattern. CONCLUSION: We suggest that increased connectivity with areas external to the Default Mode Network (DMN) reflects both compensatory recruitment of additional areas, and pathological interwining between the DMN and the salience network as part of a global ε4-dependent circuital disruption. These differences indicate that the ε4 allele is associated with a more profound degree of DMN network breakdown even in the prodromal stage of neurodegeneration.

Mechanisms and therapeutic effectiveness of pulsed electromagnetic field therapy in oncology.

Cancer is one of the most common causes of death worldwide. Available treatments are associated with numerous side effects and only a low percentage of patients achieve complete remission. Therefore, there is a strong need for new therapeutic strategies. In this regard, pulsed electromagnetic field (PEMF) therapy presents several potential advantages including non-invasiveness, safety, lack of toxicity for non-cancerous cells, and the possibility of being combined with other available therapies. Indeed, PEMF stimulation has already been used in the context of various cancer types including skin, breast, prostate, hepatocellular, lung, ovarian, pancreatic, bladder, thyroid, and colon cancer in vitro and in vivo. At present, only limited application of PEMF in cancer has been documented in humans. In this article, we review the experimental and clinical evidence of PEMF therapy discussing future perspectives in its use in oncology.

Lower serum uric acid is associated with mild cognitive impairment in early Parkinson's disease: a 4-year follow-up study.

Cognitive deficits are common in Parkinson's disease (PD) and many patients eventually develop dementia; however, its occurrence is unpredictable. Serum uric acid (UA) has been proposed as a biomarker of PD, both in the preclinical and clinical phase of the disease. The aim of this pilot study was to evaluate relationships between baseline serum UA levels and occurrence of mild cognitive impairment (MCI) at 4-year follow-up in a cohort of early PD patients. Early PD patients, not presenting concomitant diseases, cognitive impairment or treatment possibly interfering with UA levels, underwent neuropsychological testing at baseline and 4-year follow-up. UA levels were determined in serum at baseline. MCI was found in 23 out of 42 PD patients completing 4-year follow-up. Patients presenting MCI had significantly higher age at onset and lower Frontal Assessment Battery scores at baseline as compared with patients cognitively intact. Logistic regression analysis showed that both serum UA levels (OR = 0.54, p = 0.044) and age (OR = 1.16, p = 0.009) contribute to the occurrence of MCI at 4-year follow-up. Our pilot study suggests that lower levels of serum UA in the early disease stages are associated to the later occurrence of MCI. These results need to be confirmed by further studies on larger samples.

Mechanisms and therapeutic applications of electromagnetic therapy in Parkinson's disease.

Electromagnetic therapy is a non-invasive and safe approach for the management of several pathological conditions including neurodegenerative diseases. Parkinson's disease is a neurodegenerative pathology caused by abnormal degeneration of dopaminergic neurons in the ventral tegmental area and substantia nigra pars compacta in the midbrain resulting in damage to the basal ganglia. Electromagnetic therapy has been extensively used in the clinical setting in the form of transcranial magnetic stimulation, repetitive transcranial magnetic stimulation, high-frequency transcranial magnetic stimulation and pulsed electromagnetic field therapy which can also be used in the domestic setting. In this review, we discuss the mechanisms and therapeutic applications of electromagnetic therapy to alleviate motor and non-motor deficits that characterize Parkinson's disease.

Patterns of cortical thickness associated with impulse control disorders in Parkinson's disease.

Previous functional neuroimaging studies in Parkinson's disease (PD) patients with impulse control disorders (ICDs) demonstrated dysfunction of the reward network, although the extent of anatomical changes is unclear. The aim of this study was to measure brain cortical thickness and subcortical volumes, and to assess their relationship with presence and severity of symptoms, in PD patients with and without ICDs. We studied 110 PD patients (N=58 with ICDs) and 33 healthy controls (all negative for ICDs) who underwent an extensive neurological, neuropsychological, and behavioral assessment as well as structural 1.5 Tesla magnetic resonance imaging (MRI). Between-group differences in brain cortical thickness and subcortical volumes, assessed with the FreeSurfer 5.1 tool, were analyzed. In patients with ICDs, we found significant cortical thinning in fronto-striatal circuitry, specifically in the right superior orbitofrontal, left rostral middle frontal, bilateral caudal middle frontal region, and corpus callosum, as well as volume reduction in the right accumbens and increase in the left amygdala. Finally, we observed a positive association relationship between severity of impulsive symptoms and left rostral middle frontal, inferior parietal, and supramarginal areas. These results support the involvement of both reward and response inhibition networks in PD patients with ICDs. Moreover, their severity is associated with alterations in brain regions linked with reward and top-down control networks. Increased understanding of the mechanisms underlying impulsive and compulsive behaviors might help improve therapeutic strategies for these important disorders.

Identification of circulating microRNAs for the differential diagnosis of Parkinson's disease and Multiple System Atrophy.

BACKGROUND: Parkinson's disease (PD) is a progressive neurodegenerative disorder which may be misdiagnosed with atypical conditions such as Multiple System Atrophy (MSA), due to overlapping clinical features. MicroRNAs (miRNAs) are small non-coding RNAs with a key role in post-transcriptional gene regulation. We hypothesized that identification of a distinct set of circulating miRNAs (cmiRNAs) could distinguish patients affected by PD from MSA and healthy individuals. Results. Using TaqMan Low Density Array technology, we analyzed 754 miRNAs and found 9 cmiRNAs differentially expressed in PD and MSA patients compared to healthy controls. We also validated a set of 4 differentially expressed cmiRNAs in PD and MSA patients vs. controls. More specifically, miR-339-5p was downregulated, whereas miR-223(*), miR-324-3p, and mir-24 were upregulated in both diseases. We found cmiRNAs specifically deregulated in PD (downregulation of miR-30c and miR-148b) and in MSA (upregulation of miR-148b). Finally, comparing MSA and PD, we identified 3 upregulated cmiRNAs in MSA serum (miR-24, miR-34b, miR-148b). Conclusions. Our results suggest that cmiRNA signatures discriminate PD from MSA patients and healthy controls and may be considered specific, non-invasive biomarkers for differential diagnosis.

Cognitive profiling of Parkinson disease patients with mild cognitive impairment and dementia.

BACKGROUND: Prevalence of mild cognitive impairment (MCI) and dementia in Parkinson disease (PD) is variable because different classification criteria are applied and there is lack of consensus about neuropsychological tests and cut-off used for cognitive profiling. Given the important therapeutic consequences for patient management, we aimed at identifying suitable diagnostic cognitive tests and respective screening cut-off values for MCI and dementia in PD (PDD). METHODS: We evaluated 105 PD patients using an extensive neuropsychological battery categorized as PD without cognitive impairment (PD-CNT) (35%), PD-MCI (47%) and PDD (18%) based on established criteria and calculated Receiver Operating Characteristic (ROC) curves. RESULTS: We found different sensitivity and specificity among neuropsychological tests in detecting PD-MCI and PDD. In particular performance in attention/set shifting, verbal memory and language abilities, discriminated both PD-MCI and PDD from PD-CNT. Abilities involved mainly in semantic retrieval mechanisms discriminated PD-CNT from PD-MCI but also PD-MCI from PDD. Finally deficits in executive and visual-spatial abilities were only affected in PDD. CONCLUSION: Our data point to an independent and different load of each test in defining different PD cognitive statuses. These findings can help selection of appropriate cognitive batteries in longitudinal studies and definition of stage-specific therapeutic targets.

The MTHFR C677T polymorphism modifies age at onset in Parkinson's disease.

Hyperhomocysteinemia is a risk factor for Parkinson's disease (PD) and may result from genetic mutations or/and environmental factors. 5,10-methylenetetrahydrofolate reductase (MTHFR) is a folate-dependent enzyme that catalyzed remethylation of homocysteine (Hcy) and the MTHFR C677T polymorphism makes the MTHFR enzyme thermolabile causing hyperhomocysteinemia. In this study we analyzed whether two functional polymorphisms of MTHFR gene, A1298C and C677T, affect age of onset in PD. We enrolled 120 patients with sporadic PD. Patients were divided into three groups based on MTHFR C677T polymorphisms: (a) homozygotes wild type (CC) (b) heterozygotes (CT) and (c) homozygotes carriers of mutation (TT). MTHFR SNPs were analyzed using High-Resolution Melt analysis and ANOVA was performed to assess whether polymorphisms of MTHFR gene could influence age of onset. The MTHFR A1298C polymorphism had no effect on PD age at onset (p = 1.0) while there was a significant association with MTHFR C677T (p = 0.019 Bonferroni-adjusted post hoc) showing an earlier onset in CC as compared with TT. (p = 0.024). No differences were found for vascular load assessed with magnetic resonance imaging, pharmacological therapy and cognitive state for two MTHFR SNPs. Our results suggest a possible association of MTHFR C677T with age at onset of PD and may have important implications regarding the role of MTHFR.

Diagnostic and screening power of neuropsychological testing in detecting mild cognitive impairment in Parkinson's disease.

Prevalence of mild cognitive impairment (MCI) in Parkinson's disease (PD) is variable likely due to methodological differences in classification criteria and lack of consensus about neuropsychological tests used for cognitive profiling. The main objective of our study was to identify the most suitable neuropsychological tests and determine their screening and diagnostic cutoff scores for PD-MCI. A series of 104 consecutive PD patients performed an extensive neuropsychological evaluation. Individual test values were converted into Z-scores using relative published normative data. According to published criteria, PD patients were categorized as PD-CNT (PD without cognitive impairment), PD-MCI (patients performing -1.5 SDs below the mean score in at least one cognitive domain), and PDD. We used receiver operating characteristic (ROC) curves and K-means clustering analyses to calculate the best discriminating power of each neuropsychological tests in detecting PD-MCI. PD patients were categorized as follows: 55 PD-CNT (53 %), 34 PD-MCI (33 %), and 15 PDD (14 %). PD-MCI had lower education, longer disease duration and greater frequency of hallucinations than PD-CNT. We found that only the Trail Making test, Rey-Osterrieth Complex Figure Test (ROCF) copy, Frontal Assessment Battery (FAB), Digit Span Backward, and Rey's word auditory verbal learning test (RVLT) immediate recall reached significant screening and diagnostic validity in predicting PD-MCI (AUC 0.705-0.795) with cutoff scores calculated by ROC analyses lying within normal range for normative data. Specific neuropsychological tests covering verbal memory, attention/set-shifting, and visual-spatial deficits are the best predictors of MCI in PD if valid cutoff scores are used. These results have consequences for cognitive diagnosis and potentially in establishing the rate of PD cognitive decline.

A new interpretative paradigm for Conformational Protein Diseases.

Conformational Protein Diseases (CPDs) comprise over forty clinically and pathologically diverse disorders in which specific altered proteins accumulate in cells or tissues of the body. The most studied are Alzheimerß's disease, Parkinson's disease, Huntington's disease, amyotrophic lateral sclerosis, prion diseases, inclusion body myopathy, and the systemic amyloidoses. They are characterised by three dimensional conformational alterations, which are often rich in ß- structure. Proteins in this non-native conformation are highly stable, resistant to degradation, and have an enhanced tendency to aggregate with like protein molecules. The misfolded proteins can impart their anomalous properties to soluble, monomeric proteins with the same amino acid sequence by a process that has been likened to seeded crystallization. However, these potentially pathogenic proteins also have important physiological actions, which have not completely characterized. This opens up the question of what process transforms physiological actions into pathological actions and most intriguing, is why potentially dangerous proteins have been maintained during evolution and are present from yeasts to humans. In the present paper, we introduce the concept of mis-exaptation and of mis-tinkering since they may help in clarifying some of the double edged sword aspects of these proteins. Against this background an original interpretative paradigm for CPDs will be given in the frame of the previously proposed Red Queen Theory of Aging.

Role of genetic polymorphisms of the dopaminergic system in Parkinson's disease patients with impulse control disorders.

BACKGROUND: The mechanisms underlying the development of impulse control disorders (ICDs) like compulsive gambling, buying, sexual, and eating behaviors in Parkinson's disease (PD) are debated. We assessed whether allelic variants of dopamine D2 receptors (DRD2), catechol-O-methyltransferase (COMT) and dopamine transporter (DAT) were associated with the development of ICDs in PD. METHOD: We enrolled 89 idiopathic PD patients (48 without ICDs and 41 with ICDs). All patients were screened with the Minnesota Impulsive Disorders Interview (MIDI) and fulfilled DSM-IV criteria for the ICD positive cohort. Differences in the frequency of the genotypes between ICDs and non-ICDs groups were assessed using the χ(2) test. RESULTS: Genotyping was performed for variants of the DRD2 Taq1A (rs1800497), COMT Val(158)Met (rs4680), DAT1 (3' UTR 40bp VNTR). Variants of DRD2 Taq1A, COMT and DAT1 were not associated with the risk of developing ICDs. CONCLUSION: In our study, there were no differences in the frequency of variant of DRD2 Taq1A, COMT and DAT1 between the two groups. Polymorphisms of dopaminergic genes do not play a relevant role in the development of ICD in PD suggesting that ICD originate from inability to filter inappropriate behaviors triggered by dopaminergic therapy.