A Genetic Assessment of Dopamine Agonist-Induced Impulse Control Disorder in Patients With Prolactinoma.

CONTEXT: Dopamine agonist (DA)-induced impulse control disorder (ICD) represents a group of behavioral disorders that are increasingly recognized in patients with prolactinoma. OBJECTIVE: We aimed to examine the genetic component of the underlying mechanism of DA-induced ICD. METHODS: Patients with prolactinoma receiving dopamine agonist (cabergoline) treatment were included in the study. These patients were divided into 2 groups: patients who developed ICD due to DA and patients who did not. Patients were evaluated for polymorphisms of the DRD1, DRD3, COMT, DDC, GRIN2B, TPH2, OPRK1, OPRM1, SLC6A4, SLC6A3, HTR2A genes. RESULTS: Of the 72 patients with prolactinoma using cabergoline, 20 were diagnosed with ICD. When patients with and without ICD were compared according to genotype frequencies, OPRK1/rs702764, DRD3/rs6280, HTR2A/rs6313, SLC6A4/rs7224199, GRIN2B/rs7301328, TPH2/rs7305115, COMT/rs4680, DRD1/rs4532 polymorphisms significantly increased in patients with DA-induced ICD. CONCLUSION: Our results show that multiple neurotransmission systems affect DA-induced ICD in patients with prolactinoma.

Genetic prediction of impulse control disorders in Parkinson's disease.

OBJECTIVE: To develop a clinico-genetic predictor of impulse control disorder (ICD) risk in Parkinson's disease (PD). METHODS: In 5770 individuals from three PD cohorts (the 23andMe, Inc.; the University of Pennsylvania [UPenn]; and the Parkinson's Progression Markers Initiative [PPMI]), we used a discovery-replication strategy to develop a clinico-genetic predictor for ICD risk. We first performed a Genomewide Association Study (GWAS) for ICDs anytime during PD in 5262 PD individuals from the 23andMe cohort. We then combined newly discovered ICD risk loci with 13 ICD risk loci previously reported in the literature to develop a model predicting ICD in a Training dataset (n = 339, from UPenn and PPMI cohorts). The model was tested in a non-overlapping Test dataset (n = 169, from UPenn and PPMI cohorts) and used to derive a continuous measure, the ICD-risk score (ICD-RS), enriching for PD individuals with ICD (ICD+ PD). RESULTS: By GWAS, we discovered four new loci associated with ICD at p-values of 4.9e-07 to 1.3e-06. Our best logistic regression model included seven clinical and two genetic variables, achieving an area under the receiver operating curve for ICD prediction of 0.75 in the Training and 0.72 in the Test dataset. The ICD-RS separated groups of PD individuals with ICD prevalence of nearly 40% (highest risk quartile) versus 7% (lowest risk quartile). INTERPRETATION: In this multi-cohort, international study, we developed an easily computed clinico-genetic tool, the ICD-RS, that substantially enriches for subgroups of PD at very high versus very low risk for ICD, enabling pharmacogenetic approaches to PD medication selection.

Brunner syndrome associated MAOA mutations result in NMDAR hyperfunction and increased network activity in human dopaminergic neurons.

Monoamine neurotransmitter abundance affects motor control, emotion, and cognitive function and is regulated by monoamine oxidases. Among these, Monoamine oxidase A (MAOA) catalyzes the degradation of dopamine, norepinephrine, and serotonin into their inactive metabolites. Loss-of-function mutations in the X-linked MAOA gene have been associated with Brunner syndrome, which is characterized by various forms of impulsivity, maladaptive externalizing behavior, and mild intellectual disability. Impaired MAOA activity in individuals with Brunner syndrome results in bioamine aberration, but it is currently unknown how this affects neuronal function, specifically in dopaminergic (DA) neurons. Here we generated human induced pluripotent stem cell (hiPSC)-derived DA neurons from three individuals with Brunner syndrome carrying different mutations and characterized neuronal properties at the single cell and neuronal network level in vitro. DA neurons of Brunner syndrome patients showed reduced synaptic density but exhibited hyperactive network activity. Intrinsic functional properties and α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPAR)-mediated synaptic transmission were not affected in DA neurons of individuals with Brunner syndrome. Instead, we show that the neuronal network hyperactivity is mediated by upregulation of the GRIN2A and GRIN2B subunits of the N-methyl-d-aspartate receptor (NMDAR), resulting in increased NMDAR-mediated currents. By correcting a MAOA missense mutation with CRISPR/Cas9 genome editing we normalized GRIN2A and GRIN2B expression, NMDAR function and neuronal population activity to control levels. Our data suggest that MAOA mutations in Brunner syndrome increase the activity of dopaminergic neurons through upregulation of NMDAR function, which may contribute to the etiology of Brunner syndrome associated phenotypes.

Gene expression in peripheral blood mononuclear cells in impulsive aggression: Intermittent explosive disorder compared with non-aggressive healthy and psychiatric controls.

Evidence of chronic, systemic, low levels of inflammation is present in several stress-related psychiatric conditions including schizophrenia, depression, and intermittent explosive disorder (IED). We analyzed leukocyte gene expression (mRNA) to quantify the activity of pro and anti-inflammatory signaling pathways. Work performed in non-aggressive populations has uncovered a Conserved Transcriptional Response to Adversity (CTRA) characterized by an upregulation of pro-inflammatory gene transcription in chronically stressed individuals. We used pathway-based bioinformatic analyses of genome-wide transcriptional profiles of peripheral blood leukocyte samples from IED study participants (N = 45) and controls [healthy (n = 45) and psychiatric (n = 34)], with analyses focusing on the pro-inflammatory transcription control pathway mediated by the NF-kB family of transcription factors (typically upregulated in CTRA) and the antiviral transcription control pathway mediated by anti-viral response (IRF) family transcription factors (typically downregulated in CTRA). Compared with both healthy and psychiatric controls, individuals with IED had upregulated transcriptional activity of the antiviral response (IRF), but no evidence of pro-inflammatory NF-kB activation. Analyses implicated CD4 + T cells, CD8 + T cells, and B lymphocytes in IED-related transcriptional alterations, but showed no significant indication of monocyte involvement. This suggests that the inflammatory profile of IED differs substantially from that observed previously in other stress-related disorders, and may involve a pathogen-driven adaptive immune etiology.

Impulse control disorders and related behaviors in Parkinson's disease: risk factors, clinical and genetic aspects, and management.

PURPOSE OF REVIEW: To review recent findings and research directions on impulse control disorders and related behaviors (ICDRBs) in Parkinson's disease (PD). RECENT FINDINGS: Longitudinal studies found that prevalence increases during PD progression, incident ICDRBs being around 10% per year in patients treated with dopaminergic therapies. Screening tools and severity scales already developed have been validated and are available in several countries and languages. The main clinical risk factors include young age, male gender, type, doses and duration of dopaminergic therapy, PD motor severity and dyskinesia, depression, anxiety, apathy, sleep disorders, and impulsivity traits. Genetic factors are suspected by a high estimated heritability, but individual genes and variants remain to be replicated. Management of ICDRBs is centered on dopamine agonist decrease, with the risk to develop withdrawal symptoms. Cognitive behavioral therapy and subthalamic nucleus deep brain stimulation also improve ICDRBs. In the perspective of precision medicine, new individual prediction models of these disorders have been proposed, but they need further independent replication. SUMMARY: Regular monitoring of ICDRB during the course of PD is needed, particularly in the subject at high risk of developing these complications. Precision medicine will require the appropriate use of machine learning to be reached in the clinical setting.

Exploratory analysis of the genetics of impulse control disorders in Parkinson's disease using genetic risk scores.

OBJECTIVE: To study the association between impulse control disorders (ICDs) in Parkinson's disease (PD) and genetic risk scores (GRS) for 40 known or putative risk factors (e.g. depression, personality traits). BACKGROUND: In absence of published genome-wide association studies (GWAS), little is known about the genetics of ICDs in PD. GRS of related phenotypes, for which large GWAS are available, may help shed light on the genetic contributors of ICDs in PD. METHODS: We searched for GWAS on European ancestry populations with summary statistics publicly available for a broad range of phenotypes, including other psychiatric disorders, personality traits, and simple phenotypes. We separately tested their predictive ability in two of the largest PD cohorts with clinical and genetic available: the Parkinson's Progression Markers Initiative database (N = 368, 33% female, age range = [33-84]) and the Drug Interaction With Genes in Parkinson's Disease study (N = 373, 40% female, age range = [29-85]). RESULTS: We considered 40 known or putative risk factors for ICDs in PD for which large GWAS had been published. After Bonferroni correction for multiple comparisons, no GRS or the combination of the 40 GRS were significantly associated with ICDs from the analyses in each cohort separately and from the meta-analysis. CONCLUSION: Albeit unsuccessful, our approach will gain power in the coming years with increasing availability of genotypes in clinical cohorts of PD, but also from future increase in GWAS sample sizes of the phenotypes we considered. Our approach may be applied to other complex disorders, for which GWAS are not available or limited.

Integrating genetic and clinical data to predict impulse control disorders in Parkinson's disease.

BACKGROUND AND PURPOSE: Impulse control disorders (ICDs) are frequent in Parkinson's disease (PD), with associated clinical and genetic risk factors. This study was aimed at analyzing the clinical features and the genetic background that underlie ICDs in PD. METHODS: We included 353 patients with PD in this study (58.9% men, mean age 62.4 ± 10.58 years, mean age at disease onset 52.71 ± 11.94 years). We used the validated Questionnaire for Impulsive-Compulsive Disorders in Parkinson's Disease for ICDs screening. Motor, nonmotor, and treatment-related features were evaluated according to the presence of ICDs. Twenty-one variants related to dopaminergic, serotonergic, glutamatergic, and opioid neurotransmitter systems were assessed. Association studies between polymorphisms and ICDs were performed. The combination of clinical and genetic variables was analyzed with receiver operating characteristic curves to assess the predictability of experiencing ICDs. RESULTS: Impulse control disorders appeared in 25.1% of the cases. Patients with ICDs were younger and presented a higher rate of anxiety. Treatment with dopamine agonists increased the risk of ICDs and it was dose dependent (P < 0.05). Genetic association studies showed that the DOPA decarboxylase gene (DDC), rs1451375, might modulate the risk of ICDs. Plotting the clinical-genetic model, the predictability of ICDs increased 11% (area under curve = 0.80; z = 3.22, P = 0.001) when adding the genotype data for single nucleotide polymorphisms. CONCLUSIONS: Polymorphisms in DDC might act as risk markers for ICDs in PD. The predictability of experiencing ICDs increased by adding genetic factors to clinical features. It is therefore important to assess the patient's genetic background to identify individuals at risk for ICDs.

Clinical and Clinical-Pharmacogenetic Models for Prediction of the Most Common Psychiatric Complications Due to Dopaminergic Treatment in Parkinson's Disease.

BACKGROUND: The most common psychiatric complications due to dopaminergic treatment in Parkinson's disease are visual hallucinations and impulse control disorders. Their development depends on clinical and genetic factors. METHODS: We evaluated the simultaneous effect of 16 clinical and 34 genetic variables on the occurrence of visual hallucinations and impulse control disorders. Altogether, 214 Parkinson's disease patients were enrolled. Their demographic, clinical, and genotype data were obtained. Clinical and clinical-pharmacogenetic models were built by The Least Absolute Shrinkage and Selection Operator penalized logistic regression. The predictive capacity was evaluated with the cross-validated area under the receiver operating characteristic curve (AUC). RESULTS: The clinical-pharmacogenetic index for prediction of visual hallucinations encompassed age at diagnosis (OR = 0.99), rapid eye movement (REM) sleep behavior disorder (OR = 2.27), depression (OR = 1.0002), IL6 rs1800795 (OR = 0.99), GPX1 s1050450 (OR = 1.07), COMT rs165815 (OR = 0.69), MAOB rs1799836 (OR = 0.97), DRD3 rs6280 (OR = 1.32), and BIRC5 rs8073069 (OR = 0.94). The clinical-pharmacogenetic index for prediction of impulse control disorders encompassed age at diagnosis (OR = 0.95), depression (OR = 1.75), beta-blockers (OR = 0.99), coffee consumption (OR = 0.97), NOS1 rs2682826 (OR = 1.15), SLC6A3 rs393795 (OR = 1.27), SLC22A1 rs628031 (OR = 1.19), DRD2 rs1799732 (OR = 0.88), DRD3 rs6280 (OR = 0.88), and NRG1 rs3924999 (OR = 0.96). The cross-validated AUCs of clinical and clinical-pharmacogenetic models for visual hallucinations were 0.60 and 0.59, respectively. The AUCs of clinical and clinical-pharmacogenetic models for impulse control disorders were 0.72 and 0.71, respectively. The AUCs show that the addition of selected genetic variables to the analysis does not contribute to better prediction of visual hallucinations and impulse control disorders. CONCLUSIONS: Models could be improved by a larger cohort and by addition of other types of Parkinson's disease biomarkers to the analysis.

Parkinson's disease polygenic risk score is not associated with impulse control disorders: A longitudinal study.

OBJECTIVE: To examine the relationship between a Parkinson's disease (PD) polygenic risk score (PRS) and impulse control disorders (ICDs) in PD. BACKGROUND: Genome wide association studies (GWAS) have brought forth a PRS associated with increased risk of PD and younger disease onset. ICDs are frequent adverse effects of dopaminergic drugs and are also more frequent in patients with younger disease onset. It is unknown whether ICDs and PD share genetic susceptibility. METHODS: We used data from a multicenter longitudinal cohort of PD patients with annual visits up to 6 years (DIG-PD). At each visit ICDs, defined as compulsive gambling, buying, eating, or sexual behavior were evaluated by movement disorders specialists. We genotyped DNAs using the Megachip assay (Illumina) and calculated a weighted PRS based on 90 SNPs associated with PD. We estimated the association between PRS and prevalence of ICDs at each visit using Poisson generalized estimating equations, adjusted for dopaminergic treatment and other known risk factors for ICDs. RESULTS: Of 403 patients, 185 developed ICDs. Patients with younger age at onset had a higher prevalence of ICDs (p < 0.001) as well as higher PRS values (p = 0.06). At baseline, there was no association between the PRS and ICDs (overall, p = 0.84). The prevalence of ICDs increased over time similarly across the quartiles of the PRS (overall, p = 0.88; DA users, p = 0.99). CONCLUSION: Despite younger disease onset being associated with both higher PRS and ICD prevalence, our findings are not in favor of common susceptibility genes for PD and ICDs.

Trichotillomania comorbidity in a sample enriched for familial obsessive-compulsive disorder.

BACKGROUND: This study addresses the strength of associations between trichotillomania (TTM) and other DSM-IV Axis I conditions in a large sample (n = 2606) enriched for familial obsessive-compulsive disorder (OCD), to inform TTM classification. METHODS: We identified participants with TTM in the Johns Hopkins OCD Family Study (153 families) and the OCD Collaborative Genetics Study, a six-site genetic linkage study of OCD (487 families). We used logistic regression (with generalized estimating equations) to assess the strength of associations between TTM and other DSM-IV disorders. RESULTS: TTM had excess comorbidity with a number of conditions from different DSM-IV chapters, including tic disorders, alcohol dependence, mood disorders, anxiety disorders, impulse-control disorders, and bulimia nervosa. However, association strengths (odds ratios) were highest for kleptomania (6.6), pyromania (5.8), OCD (5.6), skin picking disorder (4.4), bulimia nervosa (3.5), and pathological nail biting (3.4). CONCLUSIONS: TTM is comorbid with a number of psychiatric conditions besides OCD, and it is strongly associated with other conditions involving impaired impulse control. Though DSM-5 includes TTM as an OCD-related disorder, its comorbidity pattern also emphasizes the impulsive, appetitive aspects of this condition that may be relevant to classification.

Blunted stress reactivity reveals vulnerability to early life adversity in young adults with a family history of alcoholism.

BACKGROUND AND AIMS: People with blunted stress reactivity have poor impulse control and also show increased risk for alcoholism. Exposure to early life adversity (ELA) contributes to blunted reactivity, but individual differences in susceptibility to ELA are not well understood. This study aimed to determine whether exposure to ELA has a greater impact on stress reactivity in young adults with a family history of alcoholism (FH+) compared with young adults with no family history of alcoholism (FH-). DESIGN: Observational study using linear modeling. SETTING: Oklahoma, USA. PARTICIPANTS: Seven hundred and nine young adults (398 females) recruited through community advertisement. MEASUREMENTS: We obtained heart rates and cortisol levels in subjects while undergoing public speaking and mental arithmetic stress compared with a resting control day (1418 test sessions). ELA was quantified as 0, 1 or > 1 adverse events experienced by age 15 years. FH+ people had one or two parents with an alcohol use disorder, and FH- controls had no such history for two generations. FINDINGS: Increasing levels of ELA predicted progressive blunting of cortisol and heart rate reactivity for the whole sample (Fs = 4.57 and 4.70, Ps ≤ 0.011), but examination by FH status showed that the effect of ELA was significant only among FH+ (Fs ≥ 3.5, Ps < 0.05) and absent in FH- (Ps > 0.40). This difference in ELA impact was not explained by the cortisol diurnal cycle or subjective evaluation of the stressors. CONCLUSIONS: People with a family history of alcoholism appear to be vulnerable, in terms of changes to physiological stress response, to the impact of exposure to early life adversity while people with no family history of alcoholism appear to be resilient. Blunted stress reactivity may reflect differential vulnerability to early life adversity in young adults with a family history of alcoholism.

Dopaminergic influences on risk preferences of Parkinson's disease patients.

Clinicians are increasingly recognizing impulse control disorders (ICDs) as a complication of dopaminergic treatment in Parkinson's disease (PD). Considering the pivotal role of dopamine in reward information processing, ICDs may originate from dysregulation of reward-oriented behavior, and the behavioral changes may be reflected in shifts of psychological risk preference during decision-making. We used a behavioral economics paradigm to evaluate quantitatively the risk preferences of PD patients in levodopa on and off states. We also examined age-matched healthy controls. We found that levodopa increased the subjective value and prolonged the decision time in PD patients. These effects are apparently not explained by kinematic improvements but are attributed to psychological shifts of risk preferences and increased attention during risky decision-making. The risk preferences of healthy controls were similar to those of PD on levodopa treatment. The risk preferences of PD patients were not correlated with the scores of routine cognitive batteries, suggesting that dopamine-sensitive risk preferences are independent of cognitive capacities as measured by conventional batteries, including general intelligence, memory, and frontal functioning. By contrast, apathy and ICD partially predicted the risk attitude in PD patients, suggesting a common background of limbic origin behind these properties. The present results demonstrated that dopamine deficiency in off-state PD leads to risk-avoiding behavior and levodopa treatment increases the risk preferences. Behavioral economics framework is useful to evaluate short-term psychological changes in response to levodopa in PD patients.

Behavioral Addictions as Mental Disorders: To Be or Not To Be?

Should excessive and problematic engagement in nonsubstance use behaviors be mental disorders? The fifth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5) repositioned gambling disorder in the substance use disorders section and introduced Internet gaming disorder in the research appendix; the International Classification of Diseases (ICD-11) is also considering it. This article outlines pros and cons of considering behavioral addictions as mental disorders and also reviews the DSM-5 decision-making processes. It focuses on three conditions: gambling disorder, Internet gaming disorder (IGD), and Internet addiction (IA). We detail assessment methods and prevalence rates for these conditions and outline psychiatric comorbidities, demographic and biological risk factors, and promising treatment approaches. We also briefly discuss other putative behavioral addictions: eating/food, sex, exercise, shopping, and tanning "addictions." Overall, data are inconclusive, and consistent terminology and methodology are needed to define and evaluate these conditions more fully prior to considering them mental disorders.

Behavioral addictions in early-onset Parkinson disease are associated with DRD3 variants.

BACKGROUND: Impulse control disorders (ICDs) comprise abnormal behaviors frequently found in patients with Parkinson's disease (PD) receiving antiparkinsonian medication. ICDs in PD would develop when dopaminergic treatment overstimulates the dopamine receptor D3 (DR3). Here we studied whether DR3 gene (DRD3) is associated to ICD in PD patients with early-onset (EOPD). METHODS: We performed association analysis of the rs6280 DRD3 single nucleotide variation (SNV) (Ser9Gly) in a clinical sample of 126 non early-onset PD (NEOPD) and 73 EOPD (age at onset < 45). ICD was evaluated using the Questionnaire for Impulsive-Compulsive Disorders (QUIP) in PD. RESULTS: In the total sample, we found that a younger onset of PD is linked to ICD traits with a potentially addictive reinforcement (ICDARs, behavioral addictions) (p = .017) and a trend for total ICDs (p = .078) while punding was not associated (p = .75). EOPD sample showed an increase of DRD3 C+ genotype for ICD (p = .022) and ICDARs (p = .043) but not for punding (p = .170). The post-hoc analyses including the time of evolution and Pramipexol or Ropinirole treatments, confirmed the independent effect of the DRD3 upon ICDs (p = .028) and ICDARs (p = .041) as well as the interaction between DRD3 and Pramipexol treatment upon ICDARs (OR = 4.60, 95% CI 1.20-17.632, p = .026). The NEOPD group showed no association between DRD3 and ICDs. CONCLUSIONS: We found that behavioral addictions in PD are associated with an early onset of the disease, the rs6280 DRD3 SNV and the type of dopamine agonist. Further investigation in independent samples is warranted.

Genome-Wide DNA Methylation Changes Associated with Intermittent Explosive Disorder: A Gene-Based Functional Enrichment Analysis.

Background: Intermittent explosive disorder is defined as a recurrent, problematic, and impulsive aggression that affects 3% to 4% of the US population. While behavioral genetic studies report a substantial degree of genetic influence on aggression and impulsivity, epigenetic mechanisms underlying aggression and intermittent explosive disorder are not well known. Methods: The sample included 44 subjects (22 with a DSM-5 diagnosis of intermittent explosive disorder and 22 comparable subjects without intermittent explosive disorder). Peripheral blood DNA methylome was profiled using the Illumina Infinium HumanMethylation450 Beadchip. Intermittent explosive disorder-associated genome-wide DNA methylation changes were analyzed using the CpGassoc R package, with covariates age, sex, and race being adjusted. A gene-based functional enrichment analysis was performed to identify pathways that were overrepresented by genes harboring highly differentially methylated CpG sites. Results: A total of 27 CpG sites were differentially methylated in IED participants (P<5.0×10-5), but none reached genome-wide significant threshold. Functional enrichment analysis revealed that genes mapped by these CpG sites are involved in the inflammatory/immune system, the endocrine system, and neuronal differentiation. Conclusions: Consistent with our previous studies showing an association of inflammatory response with aggressive behavior in intermittent explosive disorder subjects, our gene-based pathway analysis using differentially methylated CpG sites supports inflammatory response as an important mechanism involved in intermittent explosive disorder and reveals other novel biological processes possibly associated with intermittent explosive disorder.

Impulsive-compulsive behaviors in parkin-associated Parkinson disease.

OBJECTIVE: The aim of this multicenter, case-control study was to investigate the prevalence and severity of impulsive-compulsive behaviors (ICBs) in a cohort of patients with parkin-associated Parkinson disease (PD) compared to a group of patients without the mutation. METHODS: We compared 22 patients with biallelic parkin mutations (parkin-PD) and 26 patients negative for parkin, PINK1, DJ-1, and GBA mutations (PD-NM), matched for age at onset, disease duration, levodopa, and dopamine agonist equivalent daily dose. A semistructured interview was used to diagnose each of the following ICBs: compulsive sexual behavior, compulsive buying, binge eating, punding, hobbyism, and compulsive medication use. The Questionnaire for Impulsive-Compulsive Disorders in Parkinson's Disease-Rating Scale (QUIP-RS) was adopted to rate ICB severity. RESULTS: Frequency of patients with at least one ICB was comparable between parkin-PD and PD-NM. Nevertheless, when analyzing the distribution of specific ICBs, a higher frequency of compulsive shopping, binge eating, and punding/hobbyism was found in the parkin-PD group. Compared to PD-NM, parkin-PD patients with ICB had younger onset age and higher frequency of smokers; in 5 patients, ICB had predated PD onset. Total and partial (compulsive buying, compulsive sexual behavior, binge eating, hobbyism/punding) QUIP-RS scores were higher in patients with parkin-PD compared to patients with PD-NM. Logistic regression analysis showed that the presence of parkin mutations was associated with smoking status and higher QUIP-RS total score. CONCLUSIONS: Our data expand the parkin-associated phenotypic spectrum demonstrating higher frequency and severity of specific ICBs, and suggesting an association between the parkin genotype, smoking status, and ICB severity.

Dopamine D3 receptor Ser9Gly variant is associated with impulse control disorders in Parkinson's disease patients.

INTRODUCTION: Impulse control disorders (ICD) are reported to occur at variable frequencies in different ethnic groups. Genetic vulnerability is suspected to underlie the individual risk for ICD. We investigated whether the allelic variants of dopamine (DRD3), glutamate (GRIN2B) and serotonin (HTR2A) receptors are linked to ICD in Indian Parkinson's disease (PD) patients. METHODS: We conducted a prospective, case-control study which included PD patients (70 with ICD, 100 without ICD categorized after direct psychiatric interview of patient and caregiver) and 285 healthy controls. Single nucleotide polymorphism (SNP) variants of DRD3 p.S9G (rs6280), GRIN2B c.2664C>T (rs1806201) and HTR2A c.102T>C (rs6313) were genotyped. RESULTS: Multivariate regression analysis revealed that DRD3 p.Ser9Gly (rs6280) heterozygous variant CT (OR = 2.22, 95% CI: 1.03-4.86, p = 0.041), higher daily Levodopa equivalent doses (LED) of drugs (for 100 mg LED, OR = 1.14, 95% CI: 1.01-1.29, p = 0.041), current dopamine agonist but not Levodopa use (OR = 2.16, 95% CI: 1.03-4.55, p = 0.042) and age of onset of motor symptoms under 50 years (OR 2.09, 95% CI: 1.05-4.18, p = 0.035) were independently associated with ICD. CONCLUSION: DRD3 p.Ser9Gly (rs6280) CT genotype is associated with ICD in Indian PD patients and this association is novel. Enhanced D3 receptor affinity due to gain-of-function conferred by the glycine residues could impair reward-risk assessment in the mesolimbic system and contribute to development of impulsive behaviour, in carriers of this genotype.

Clinical-genetic model predicts incident impulse control disorders in Parkinson's disease.

OBJECTIVES: Impulse control disorders (ICD) are commonly associated with dopamine replacement therapy (DRT) in patients with Parkinson's disease (PD). Our aims were to estimate ICD heritability and to predict ICD by a candidate genetic multivariable panel in patients with PD. METHODS: Data from de novo patients with PD, drug-naïve and free of ICD behaviour at baseline, were obtained from the Parkinson's Progression Markers Initiative cohort. Incident ICD behaviour was defined as positive score on the Questionnaire for Impulsive-Compulsive Disorders in PD. ICD heritability was estimated by restricted maximum likelihood analysis on whole exome sequencing data. 13 candidate variants were selected from the DRD2, DRD3, DAT1, COMT, DDC, GRIN2B, ADRA2C, SERT, TPH2, HTR2A, OPRK1 and OPRM1 genes. ICD prediction was evaluated by the area under the curve (AUC) of receiver operating characteristic (ROC) curves. RESULTS: Among 276 patients with PD included in the analysis, 86% started DRT, 40% were on dopamine agonists (DA), 19% reported incident ICD behaviour during follow-up. We found heritability of this symptom to be 57%. Adding genotypes from the 13 candidate variants significantly increased ICD predictability (AUC=76%, 95% CI (70% to 83%)) compared to prediction based on clinical variables only (AUC=65%, 95% CI (58% to 73%), p=0.002). The clinical-genetic prediction model reached highest accuracy in patients initiating DA therapy (AUC=87%, 95% CI (80% to 93%)). OPRK1, HTR2A and DDC genotypes were the strongest genetic predictive factors. CONCLUSIONS: Our results show that adding a candidate genetic panel increases ICD predictability, suggesting potential for developing clinical-genetic models to identify patients with PD at increased risk of ICD development and guide DRT management.

New insights into Brunner syndrome and potential for targeted therapy.

We report two families with Brunner syndrome living in one state of Australia. The first family had a predicted protein-truncating variant of monoamine oxidase A (MAOA) (p.S251KfsX2). Affected males had mild intellectual disability (ID), obsessive behaviour, limited friendships and were introverted and placid during clinical interview. The family disclosed episodic explosive aggression after a diagnosis was made. The second family had a missense variant in MAOA (p.R45W). Affected males had borderline-mild ID, attention deficit disorder and limited friendships. One had a history of explosive aggression in childhood and episodic symptoms of flushing, headaches and diarrhoea. Their carrier mother had normal intelligence but similar episodic symptoms. Characteristic biochemical abnormalities included high serum serotonin and urinary metanephrines and low urinary 5-hydroxyindoleacetic acid (5-HIAA) and vanillylmandelic acid (VMA). Symptomatic individuals in the second family had particularly high serotonin levels, and treatment with a serotonin reuptake inhibitor and dietary modification resulted in reversal of biochemical abnormalities, reduction of 'serotonergic' symptoms and behavioural improvement. Brunner syndrome should be considered as a cause of mild ID with paroxysmal behavioural symptoms. It can be screened for with serum/urine metanephrine and serotonin measurement. Cautious treatment with a serotonin reuptake inhibitor, dietary modifications and avoidance of medications contraindicated in patients on monoamine oxidase inhibitors can improve symptoms.

[Phenotypic variability of the 1q21.1 microdeletion syndrome in members of the same family: relevance of detection of neuropsychiatric disorders for diagnosis of genetic syndromes]. / Variabilidad del fenotipo del sindrome de microdelecion 1q21.1 dentro de una misma familia: importancia de la deteccion de trastornos neuropsiquiatricos para el diagnostico de sindromes geneticos.

INTRODUCTION: 1q21.1 microdeletion syndrome is a caused by a recurrent deletion of the 1q21.1 copy-number variant, which spans 800 kb and includes at least seven genes. It is associated with a variable phenotype. Neuropsychiatric abnormalities have been previously described in many of the previously reported cases, but its true prevalence is unknown. AIM: To illustrate the phenotypic variability in 1q21.1 microdeletion syndrome. CASE REPORTS: Four individuals of the same kindred harboring a 1.74-Mb deletion within 1q21.1 are included. In our patients a heterogeneous phenotype is recognized. Neuropsychiatric disorders or more specifically impulse control disorders were common to all the four cases that we present. CONCLUSIONS: 1q21.1 microdeletion syndrome is phenotypically heterogeneous even among members of the same family. Behavioral or neuropsychiatric abnormalities are frequent. Paucisymptomatic forms with individuals presenting exclusively psychiatric disorders have been identified.

TITLE: Variabilidad del fenotipo del sindrome de microdelecion 1q21.1 dentro de una misma familia: importancia de la deteccion de trastornos neuropsiquiatricos para el diagnostico de sindromes geneticos.Introduccion. El sindrome de microdelecion 1q21.1 esta causado por una delecion recurrente de aproximadamente 800 kb que incluye al menos siete genes y se asocia a un fenotipo variable. Esta variacion en el numero de copias patogenica puede aparecer de novo o ser heredada de uno de los progenitores. La presencia de trastornos psiquiatricos se ha descrito en muchos de los casos publicados, pero se desconoce su prevalencia exacta. Objetivo. Exponer la variabilidad fenotipica de los individuos que presentan una microdelecion 1q21.1. Casos clinicos. Se incluyen cuatro individuos portadores de una delecion de 1,74 Mb en 1q21.1, todos miembros de la misma familia. El estudio genetico del caso indice se llevo a cabo mediante array de hibridacion genomica comparada, y el del resto de familiares mediante hibridacion in situ fluorescente, con una sonda especifica para la region delecionada. Los individuos presentan un fenotipo heterogeneo, y es comun a todos ellos la presencia de alteraciones psiquiatricas o del comportamiento, con un claro predominio de la presencia de trastornos relacionados con las dificultades para el control de impulsos en sus diferentes subtipos. Conclusiones. El sindrome de microdelecion 1q21.1 es fenotipicamente heterogeneo, incluso entre los miembros de una misma familia. Destaca la presencia de alteraciones psiquiatricas o del comportamiento como rasgo comun en todos los pacientes que presentamos. Existen formas paucisintomaticas en las que el individuo portador de la delecion presenta exclusivamente alteraciones psiquiatricas.