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1.  Relationship Of Mediterranean Diet And Caloric Intake To Phenoconversion In Huntington Disease 
JAMA neurology  2013;70(11):1382-1388.
Adherence to Mediterranean-type diet (MeDi) may delay onset of Alzheimer's and Parkinson's disease. Whether adherence to MeDi affects time to phenoconversion in Huntington’s Disease (HD), a highly penetrant, single gene disorder, is unknown.
To determine if MeDi modifies the time to clinical onset of HD ('phenoconversion') in premanifest carriers participating in Prospective Huntington At Risk Observational Study (PHAROS), and to examine the effects of BMI and caloric intake on time to phenoconversion.
A prospective cohort study.
41 Huntington Study Group sites in the US and Canada.
1001 participants were enrolled in PHAROS between July 1999 and January 2004, and were followed every 9 months until 2010. A total of 211 participants aged 26–57 with an expanded CAG repeat (≥37) were included in the current study.
A semi-quantitative food frequency questionnaire (FFQ) was administered 33 months after baseline. We calculated daily gram intake for dairy, meat, fruit, vegetables, legumes, cereals, fish, monounsaturated and saturated fatty-acids, and alcohol, and constructed MeDi scores (0–9); higher scores indicate higher adherence. Demographics, medical history, BMI, and Unified Huntington's Disease Rating Scale (UHDRS) were collected.
Main Outcome Measure
Cox proportional hazards models to determine the association of MeDi and phenoconversion.
Age, caloric intake, gender, education, and UHDRS motor scores did not differ among MeDi tertiles (0–3, 4–5, 6–9). The highest BMI was associated with lowest adherence to MeDi. 31 participants phenoconverted. In a model adjusted for age, CAG, and caloric intake, MeDi was not associated with phenoconversion (p for trend=0.14 for tertile of MeDi, and p=0.22 for continuous MeDi). When individual diet components of MeDi were analyzed, higher dairy consumption (hazard ratio 2.36; 1.0–5.57; p=0.051) and higher caloric intake (p=0.035) were associated with risk of phenoconversion.
Conclusion and Relevance
MeDi was not associated with phenoconversion, however higher consumption of dairy products had a two-fold increased risk, and may be a surrogate for lower urate levels (associated with faster progression in manifest HD). Studies of diet and energy expenditure in premanifest HD may provide data for interventions to modify specific components of diet that may delay the onset of HD.
PMCID: PMC4040231  PMID: 24000094
Huntington disease; nutritional; cohort
2.  Attitudes and Practices Among Internists Concerning Genetic Testing 
Journal of genetic counseling  2012;22(1):90-100.
Many questions remain concerning whether, when, and how physicians order genetic tests, and what factors are involved in their decisions. We surveyed 220 internists from two academic medical centers about their utilization of genetic testing. Rates of genetic utilizations varied widely by disease. Respondents were most likely to have ordered tests for Factor V Leiden (16.8%), followed by Breast/Ovarian Cancer (15.0%). In the past 6 months, 65% had counseled patients on genetic issues, 44% had ordered genetic tests, 38.5% had referred patients to a genetic counselor or geneticist, and 27.5% had received ads from commercial labs for genetic testing. Only 4.5% had tried to hide or disguise genetic information, and <2% have had patients report genetic discrimination. Only 53.4% knew of a geneticist/genetic counselor to whom to refer patients. Most rated their knowledge as very/somewhat poor concerning genetics (73.7%) and guidelines for genetic testing (87.1%). Most felt needs for more training on when to order tests (79%), and how to counsel patients (82%), interpret results (77.3%), and maintain privacy (80.6%). Physicians were more likely to have ordered a genetic test if patients inquired about genetic testing (p<.001), and if physicians had a geneticist/genetic counselor to whom to refer patients (p<.002), had referred patients to a geneticist/genetic counselor in the past 6 months, had more comfort counseling patients about testing (p<.019), counseled patients about genetics, larger practices (p<.032), fewer African-American patients (p<.027), and patients who had reported genetic discrimination (p<.044). In a multiple logistic regression, ordering a genetic test was associated with patients inquiring about testing, having referred patients to a geneticist/genetic counselor and knowing how to order tests., These data suggest that physicians recognize their knowledge deficits, and are interested in training. These findings have important implications for future medical practice, research, and education.
PMCID: PMC3433636  PMID: 22585186
genetic testing; medical education; doctor-patient communication; ethics; genetic discrimination; decision-making; genetic counseling
3.  Views of internists towards uses of PGD 
Reproductive biomedicine online  2012;26(2):142-147.
Preimplantation genetic diagnosis (PGD) is increasingly available, but how physicians view it is unclear. Internists are gatekeepers and sources of information, often treating disorders for which PGD is possible. This quantitative study surveyed 220 US internists, who were found to be divided. Many would recommend PGD for cystic fibrosis (CF; 33.7%), breast cancer (BRCA; 23.4%), familial adenomatous polyposis (FAP; 20.6%) and familial hypertrophic cardiomyopathy (19.9%), but few for social sex selection (5.2%); however, in each case, >50% were unsure. Of those surveyed, 4.9% have suggested PGD to patients. Only 7.1% felt qualified to answer patient questions about it. Internists who would refer for PGD had completed medical training less recently and, for CF, were more likely to have privately insured patients (P < 0.033) and patients who reported genetic discrimination (P < 0.013). Physicians more likely to refer for BRCA and FAP were less likely to have patients ask about genetic testing. This study suggests that internists often feel they have insufficient knowledge about it and may refer for it based on limited understanding. They view possible uses of PGD differently, partly reflecting varying ages of onset and disease treatability. These data have critical implications for training, research and practice.
PMCID: PMC3565017  PMID: 23276655
assisted reproductive technology; ethics; IVF
4.  Lack of Association Between Cancer History and PARKIN Genotype: a Family Based Study in PARKIN/Parkinson’s Families 
Genes, chromosomes & cancer  2012;51(12):1109-1113.
A number of publications have attributed a tumor suppressive (TS) function to PARKIN, a gene associated with recessive familial early-onset Parkinson’s disease (EOPD). Discoveries of PARKIN deletions and point mutations in tumors, functional studies, and data from mouse models have been presented to support the hypothesis. We have asked whether PARKIN mutations are associated with history of cancer in humans. We interviewed 431 participants who were screened for PARKIN mutations, including 149 EOPD cases and their family members, who were unaware of mutation status. We found no significant difference in self-reported history of cancer among carriers of one or two PARKIN mutations and non-carriers, odds ratio 0.75 (95% confidence interval 0.27-1.83). In particular, no increase in cancer history was seen among homozygous and compound heterozygous mutation carriers compared to non-carriers. Therefore, we hypothesize that published studies attributing TS capability to PARKIN merit further exploration and we present a reevaluation of these data with respect to patterns of mutation frequencies in normal and cancer cells. We conclude that although Parkin may exert a suppressive effect in mice, further studies are required prior to assigning a TS function to PARKIN in humans.
PMCID: PMC3465486  PMID: 22927236
Tumor suppressor; PARKIN - Early-onset Parkinson’s cohort; cancer risk
5.  A Multicenter Study of Glucocerebrosidase Mutations in Dementia With Lewy Bodies 
JAMA neurology  2013;70(6):10.1001/jamaneurol.2013.1925.
While mutations in glucocerebrosidase (GBA1) are associated with an increased risk for Parkinson disease (PD), it is important to establish whether such mutations are also a common risk factor for other Lewy body disorders.
To establish whether GBA1 mutations are a risk factor for dementia with Lewy bodies (DLB).
We compared genotype data on patients and controls from 11 centers. Data concerning demographics, age at onset, disease duration, and clinical and pathological features were collected when available. We conducted pooled analyses using logistic regression to investigate GBA1 mutation carrier status as predicting DLB or PD with dementia status, using common control subjects as a reference group. Random-effects meta-analyses were conducted to account for additional heterogeneity.
Eleven centers from sites around the world performing genotyping.
Seven hundred twenty-one cases met diagnostic criteria for DLB and 151 had PD with dementia. We compared these cases with 1962 controls from the same centers matched for age, sex, and ethnicity.
Main Outcome Measures
Frequency of GBA1 mutations in cases and controls.
We found a significant association between GBA1 mutation carrier status and DLB, with an odds ratio of 8.28 (95% CI, 4.78–14.88). The odds ratio for PD with dementia was 6.48 (95% CI, 2.53–15.37). The mean age at diagnosis of DLB was earlier in GBA1 mutation carriers than in noncarriers (63.5 vs 68.9 years; P<.001), with higher disease severity scores.
Conclusions and Relevance
Mutations in GBA1 are a significant risk factor for DLB. GBA1 mutations likely play an even larger role in the genetic etiology of DLB than in PD, providing insight into the role of glucocerebrosidase in Lewy body disease.
PMCID: PMC3841974  PMID: 23588557
6.  Lower cognitive performance in healthy G2019S LRRK2 mutation carriers 
Neurology  2012;79(10):1027-1032.
To assess cognitive abilities of healthy first-degree relatives of Ashkenazi patients with Parkinson disease (PD), carriers of the G2019S mutation in the LRRK2 gene.
In this observational study, 60 consecutive healthy first-degree relatives (aged 50.9 ± 6.2 years; 48% male; 30 G2019S carriers) were assessed using a computerized cognitive program, the Montreal Cognitive Assessment questionnaire, the Unified Parkinson's Disease Rating Scale Part III, and the Geriatric Depression Scale.
G2019S carriers scored significantly lower on the computerized executive function index (p = 0.04) and on specific executive function tasks (Stroop test, p = 0.007).
Carrying the LRRK2 G2019S mutation was associated with lower executive performance in a population at risk for PD.
PMCID: PMC3430708  PMID: 22914834
7.  Increased rate of sporadic and recurrent rare genic copy number variants in Parkinson's disease among Ashkenazi Jews 
To date, only one genome-wide study has assessed the contribution of copy number variants (CNVs) to Parkinson's disease (PD). We conducted a genome-wide scan for CNVs in a case–control dataset of Ashkenazi Jewish (AJ) origin (268 PD cases and 178 controls). Using high-confidence CNVs, we examined the global genome wide burden of large (≥100 kb) and rare (≤1% in the dataset) CNVs between cases and controls. A total of 986 such CNVs were observed in our dataset of 432 subjects. Overall global burden analyses did not reveal significant differences between cases and controls in CNV rate, distribution of deletions or duplications or number of genes affected by CNVs. Overall deletions (total CNV size and ≥2× frequency) were found 1.4 times more often in cases than in controls (P = 0.019). The large CNVs (≥500 kb) were also significantly associated with PD (P = 0.046, 1.24-fold higher in cases than in controls). Global burden was elevated for rare CNV regions. Specifically, for OVOS2 on Chr12p11.21, CNVs were observed only in PD cases (n = 7) but not in controls (P = 0.028) and this was experimentally validated. A total of 81 PD cases carried a rare genic CNV that was absent in controls. Ingenuity pathway analysis (IPA) identified ATXN3, FBXW7, CHCHD3, HSF1, KLC1, and MBD3 in the same disease pathway with known PD genes.
PMCID: PMC3782064  PMID: 24073418
Ashkenazi Jews; candidate genes; case–control study; CNV; Parkinson's disease
8.  TAA repeat variation in the GRIK2 gene does not influence age at onset in Huntington's disease 
Huntington's disease is a neurodegenerative disorder caused by an expanded CAG trinucleotide repeat whose length is the major determinant of age at onset but remaining variation appears to be due in part to the effect of genetic modifiers. GRIK2, which encodes GluR6, a mediator of excitatory neurotransmission in the brain, has been suggested in several studies to be a modifier gene based upon a 3′ untranslated region TAA trinucleotide repeat polymorphism. Prior to investing in detailed studies of the functional impact of this polymorphism, we sought to confirm its effect on age at onset in a much larger dataset than in previous investigations. We genotyped the HD CAG repeat and the GRIK2 TAA repeat in DNA samples from 2,911 Huntington's disease subjects with known age at onset, and tested for a potential modifier effect of GRIK2 using a variety of statistical approaches. Unlike previous reports, we detected no evidence of an influence of the GRIK2 TAA repeat polymorphism on age at motor onset. Similarly, the GRIK2 polymorphism did not show significant modifier effect on psychiatric and cognitive age at onset in HD. Comprehensive analytical methods applied to a much larger sample than in previous studies do not support a role for GRIK2 as a genetic modifier of age at onset of clinical symptoms in Huntington's disease.
PMCID: PMC3752397  PMID: 22771793
Huntington's disease (HD); Age at onset; GRIK2; Genetic modifier
9.  CCL3L1 gene copy number in individuals with and without HIV-associated neurocognitive disorder 
Current biomarker findings  2012;2012(2):1-6.
CCL3L1 copy number variation has been implicated as a marker for susceptibility and immunity to human immunodeficiency virus (HIV)-1 infection and its pathogenic sequelae. Some of these findings have been confirmed in several, but not all, subsequent independent cohort studies. A three-fold risk for the development of HIV-associated dementia was reported in individuals possessing a CCL3L1 copy number below the ethnic group median combined with a detrimental CCR5 genotype. With the availability of antiretroviral therapy since 1996, there has been a significant decline in HIV-associated dementia, and milder forms of HIV-associated neurocognitive impairment (HAND) are now most prevalent. Moreover, patients are living longer with HIV-1 infection and it is recognized that aging may be a contributory factor to the development of cognitive disorder. Thus, the need for biomarkers that can be used in clinical practice to identify and provide optimal treatment for those at increased risk for HAND is great. HAND affects 20%–30% of HIV-infected individuals, and several genetic loci which have been shown to confer susceptibility to HIV infection may also modulate the development of neurocognitive disorder. The aim of this study was to determine whether CCL3L1 chemokine gene copy number in self-defined ethnic groups could differentiate HIV-infected individuals with and without HAND.
Genomic DNA was isolated from buccal swabs or peripheral blood mononuclear cells obtained from HIV-infected patients with or without a diagnoses of neurocognitive dysfunction in the Northeast AIDS Dementia Cohort and National NeuroAIDS Tissue Consortium. To maintain a uniform standard, a quantitative polymerase chain reaction design similar to previous studies using Taqman probes and fixed input DNA between 2 ng and 10 ng was used to determine a CCL3L1 copy number. Standard curves with two-fold dilutions from 25 ng to 1.56 ng were generated. CCL3L1 copy number was determined in triplicate in 262 subjects using quantitative polymerase chain reaction and the relative quantitation method. Data were analyzed using analysis of variance, with significance defined as P < 0.05 and Bonferroni post hoc tests.
Significant differences as determined by analysis of variance in CCL3L1 copy number between African-Americans and Caucasians (P < 0.0001) were found, highlighting ethnic group differences in the copy number of this gene. However, there were no differences in CCL3L1 copy number across the neurocognitive groups within each ethnic group. The median CCL3L1 copy number in African-Americans of two and Caucasians of one in this study was significantly lower than the previously reported ethnic group means of two and four copies, respectively. A higher prevalence of abnormal cognition with a relative risk of four was seen in African-Americans versus Caucasians.
Based on this nested case-control study, CCL3L1 copy number alone may not be useful for distinguishing between individuals at risk for mild or severe neurocognitive disorder. Additional larger cohort studies are required to determine whether CCL3L1 copy number in combination with polymorphisms in other genes known to contribute to HIV risk will be useful in identifying those at increased risk for HAND.
PMCID: PMC3693394  PMID: 23814703
neurological; HIV-associated dementia; HAND; chemokine; copy number; African-American; Caucasian
10.  A 6-month, randomized, double-blind, placebo-controlled pilot discontinuation trial following response to haloperidol treatment of psychosis and agitation in Alzheimer’s disease 
In patients with Alzheimer’s disease (AD) with psychosis or agitation that respond to haloperidol treatment, to evaluate the risk of relapse following discontinuation.
In outpatients with AD with symptoms of psychosis or agitation, responders to 20 weeks of haloperidol (0.5 to 5 mg daily) were randomized to a 24-week, double-blind pilot trial of discontinuation on placebo versus continuation haloperidol. Phase A response criteria were minimum 50% reduction in 3 target symptoms, and improvement on the Clinical Global Impression-Change (CGI-C) score for psychosis/agitation. Phase B relapse criteria required 50% worsening in target symptoms and on the CGI-C. Alpha=0.1 was the significance criterion in this pilot study.
Of 44 patients, 22 patients responded in Phase A. The sum score of target symptoms, and Brief Psychiatric Rating Scale psychosis and hostile suspiciousness factor scores, decreased in Phase A (p’s < .001). Extrapyramidal signs increased in Phase A (p < .01). Of 22 responders, 21 patients entered Phase B, and 20 had at least one follow-up visit. Four of 10 patients (40%) on continuation haloperidol relapsed compared to 8 of 10 patients on placebo (80%, χ2=3.3, p=0.07). In survival analyses, time to relapse was shorter on placebo than haloperidol (χ2=4.1, p=0.04).
Haloperidol open treatment was efficacious, and relapse was greater on placebo than with haloperidol continuation. In patients with AD who have psychosis or agitation and respond to antipsychotic medication, the increased risk of relapse after discontinuation needs to be weighed against the side effects associated with continuing the medication.
PMCID: PMC3685500  PMID: 21845596
Antipsychotic; discontinuation; Alzheimer’s disease
11.  Candidate glutamatergic and dopaminergic pathway gene variants do not influence Huntington’s disease motor onset 
Neurogenetics  2013;14:173-179.
Huntington’s disease (HD) is a neurodegenerative disorder characterized by motor, cognitive, and behavioral disturbances. It is caused by the expansion of the HTT CAG repeat, which is the major determinant of age at onset (AO) of motor symptoms. Aberrant function of N-methyl-D-aspartate receptors and/or overexposure to dopamine has been suggested to cause significant neurotoxicity, contributing to HD pathogenesis. We used genetic association analysis in 1,628 HD patients to evaluate candidate polymorphisms in N-methyl-D-aspartate receptor subtype genes (GRIN2A rs4998386 and rs2650427, and GRIN2B rs1806201) and functional polymorphisms in genes in the dopamine pathway (DAT1 3′ UTR 40-bp variable number tandem repeat (VNTR), DRD4 exon 3 48-bp VNTR, DRD2 rs1800497, and COMT rs4608) as potential modifiers of the disease process. None of the seven polymorphisms tested was found to be associated with significant modification of motor AO, either in a dominant or additive model, after adjusting for ancestry. The results of this candidate-genetic study therefore do not provide strong evidence to support a modulatory role for these variations within glutamatergic and dopaminergic genes in the AO of HD motor manifestations.
PMCID: PMC3825533  PMID: 23644918
Huntington’s disease; Glutamate receptors; Dopamine pathway; Genetic modifiers
12.  Clinical and pathological characteristics of LRRK2 G2019S patients with PD 
Journal of Molecular Neuroscience  2011;47(1):139-143.
To describe the neuropathologic findings in three LRRK2 G2019S carriers with Parkinson’s disease (PD).
We cross referenced a list of 956 PD individuals that had been previously genotyped in clinical studies at Columbia University, with 282 subjects with a parkinsonian syndrome who came to autopsy in our brain bank since 1991. We found three autopsies of G2019S mutation carriers. Pathological analyses of the samples were blind to the genetic findings. We retrospectively reviewed the clinical records of the three patients.
All three had a clinical and pathological diagnosis of PD. Cognitive impairment was a late feature in two out of three patients. Cortical involvement varied significantly: one had diffuse Lewy Body (LB) pathology, tau inclusions and amyloid pathology consistent with advanced Alzheimer’s disease; one had diffuse cortical LB and one had only brainstem predominant LB pathology.
Cognitive impairment may be a long term complication in G2019S mutation carriers. However, the extent of cortical involvement is variable. Larger longitudinal follow up of LRRK2 G2019S mutation carriers is required to assess for risk factors for cortical involvement and dementia.
PMCID: PMC3335886  PMID: 22194196
Parkinson’s disease; Lewy Bodies; LRRK2 gene mutation; Dementia
13.  Predicting Disease Onset from Mutation Status Using Proband and Relative Data with Applications to Huntington’s Disease 
Huntington’s disease (HD) is a progressive neurodegenerative disorder caused by an expansion of CAG repeats in the IT15 gene. The age-at-onset (AAO) of HD is inversely related to the CAG repeat length and the minimum length thought to cause HD is 36. Accurate estimation of the AAO distribution based on CAG repeat length is important for genetic counseling and the design of clinical trials. In the Cooperative Huntington’s Observational Research Trial (COHORT) study, the CAG repeat length is known for the proband participants. However, whether a family member shares the huntingtin gene status (CAG expanded or not) with the proband is unknown. In this work, we use the expectation-maximization (EM) algorithm to handle the missing huntingtin gene information in first-degree family members in COHORT, assuming that a family member has the same CAG length as the proband if the family member carries a huntingtin gene mutation. We perform simulation studies to examine performance of the proposed method and apply the methods to analyze COHORT proband and family combined data. Our analyses reveal that the estimated cumulative risk of HD symptom onset obtained from the combined data is slightly lower than the risk estimated from the proband data alone.
PMCID: PMC3589804  PMID: 23476655
14.  Meta-analysis of Parkinson disease: Identification of a novel locus, RIT2 
Annals of Neurology  2012;71(3):370-384.
Genome-wide association (GWAS) methods have identified genes contributing to Parkinson disease (PD); we sought to identify additional genes associated with PD susceptibility.
A two stage design was used. First, individual level genotypic data from five recent PD GWAS (Discovery Sample: 4,238 PD cases and 4,239 controls) were combined. Following imputation, a logistic regression model was employed in each dataset to test for association with PD susceptibility and results from each dataset were meta-analyzed. Second, 768 SNPs were genotyped in an independent Replication Sample (3,738 cases and 2,111 controls).
Genome-wide significance was reached for SNPs in SNCA (rs356165, G: odds ratio (OR)=1.37; p=9.3 × 10−21), MAPT (rs242559, C: OR=0.78; p=1.5 × 10−10), GAK/DGKQ (rs11248051, T:OR=1.35; p=8.2 × 10−9/ rs11248060, T: OR=1.35; p=2.0×10−9), and the HLA region (rs3129882, A: OR=0.83; p=1.2 × 10−8), which were previously reported. The Replication Sample confirmed the associations with SNCA, MAPT, and the HLA region and also with GBA (E326K OR=1.71; p=5 × 10−8 Combined Sample) (N370 OR=3.08; p=7 × 10−5 Replication sample). A novel PD susceptibility locus, RIT2, on chromosome 18 (rs12456492; p=5 × 10−5 Discovery Sample; p=1.52 × 10−7 Replication sample; p=2 × 10−10 Combined Sample) was replicated. Conditional analyses within each of the replicated regions identified distinct SNP associations within GBA and SNCA, suggesting that there may be multiple risk alleles within these genes.
We identified a novel PD susceptibility locus, RIT2, replicated several previously identified loci, and identified more than one risk allele within SNCA and GBA.
PMCID: PMC3354734  PMID: 22451204
15.  Familial Parkinson's disease iPSCs show cellular deficits in mitochondrial responses that can be pharmacologically rescued 
Science translational medicine  2012;4(141):141ra90.
Parkinson's disease (PD) is a common neurodegenerative disease caused by genetic and environmental factors. We analyzed induced pluripotent stem cell (iPSC)-derived neural cells from PD patients and presymptomatic individuals carrying mutations in the PINK1 and LRRK2 genes, and healthy control subjects. We measured several aspects of mitochondrial responses in the iPSC-derived neural cells including production of reactive oxygen species, mitochondrial respiration, proton leakage and intraneuronal movement of mitochondria. Cellular vulnerability associated with mitochondrial function in iPSC-derived neural cells from PD patients and at-risk individuals could be rescued with coenzyme Q10, rapamycin or the LRRK2 kinase inhibitor GW5074. Analysis of mitochondrial responses in iPSC-derived neural cells from PD patients carrying different mutations provides insights into convergence of cellular disease mechanisms between different familial forms of PD and highlights the importance of oxidative stress and mitochondrial dysfunction in PD.
PMCID: PMC3462009  PMID: 22764206
16.  Learning fast accurate movements requires intact frontostriatal circuits 
The basal ganglia are known to play a crucial role in movement execution, but their importance for motor skill learning remains unclear. Obstacles to our understanding include the lack of a universally accepted definition of motor skill learning (definition confound), and difficulties in distinguishing learning deficits from execution impairments (performance confound). We studied how healthy subjects and subjects with a basal ganglia disorder learn fast accurate reaching movements. We addressed the definition and performance confounds by: (1) focusing on an operationally defined core element of motor skill learning (speed-accuracy learning), and (2) using normal variation in initial performance to separate movement execution impairment from motor learning abnormalities. We measured motor skill learning as performance improvement in a reaching task with a speed-accuracy trade-off. We compared the performance of subjects with Huntington's disease (HD), a neurodegenerative basal ganglia disorder, to that of premanifest carriers of the HD mutation and of control subjects. The initial movements of HD subjects were less skilled (slower and/or less accurate) than those of control subjects. To factor out these differences in initial execution, we modeled the relationship between learning and baseline performance in control subjects. Subjects with HD exhibited a clear learning impairment that was not explained by differences in initial performance. These results support a role for the basal ganglia in both movement execution and motor skill learning.
PMCID: PMC3826079  PMID: 24312037
motor skill; kinematics; reaching; striatum; basal ganglia; movement disorder; neurodegenerative; neurological
17.  Creation of an Open-Access, Mutation-Defined Fibroblast Resource for Neurological Disease Research 
PLoS ONE  2012;7(8):e43099.
Our understanding of the molecular mechanisms of many neurological disorders has been greatly enhanced by the discovery of mutations in genes linked to familial forms of these diseases. These have facilitated the generation of cell and animal models that can be used to understand the underlying molecular pathology. Recently, there has been a surge of interest in the use of patient-derived cells, due to the development of induced pluripotent stem cells and their subsequent differentiation into neurons and glia. Access to patient cell lines carrying the relevant mutations is a limiting factor for many centres wishing to pursue this research. We have therefore generated an open-access collection of fibroblast lines from patients carrying mutations linked to neurological disease. These cell lines have been deposited in the National Institute for Neurological Disorders and Stroke (NINDS) Repository at the Coriell Institute for Medical Research and can be requested by any research group for use in in vitro disease modelling. There are currently 71 mutation-defined cell lines available for request from a wide range of neurological disorders and this collection will be continually expanded. This represents a significant resource that will advance the use of patient cells as disease models by the scientific community.
PMCID: PMC3428297  PMID: 22952635
18.  Population stratification may bias analysis of PGC-1α as a modifier of age at Huntington disease motor onset 
Human Genetics  2012;131(12):1833-1840.
Huntington’s disease (HD) is an inherited neurodegenerative disorder characterized by motor, cognitive and behavioral disturbances, caused by the expansion of a CAG trinucleotide repeat in the HD gene. The CAG allele size is the major determinant of age at onset (AO) of motor symptoms, although the remaining variance in AO is highly heritable. The rs7665116 SNP in PPARGC1A, encoding the mitochondrial regulator PGC-1α, has been reported to be a significant modifier of AO in three European HD cohorts, perhaps due to affected cases from Italy. We attempted to replicate these findings in a large collection of (1,727) HD patient DNA samples of European origin. In the entire cohort, rs7665116 showed a significant effect in the dominant model (p value = 0.008) and the additive model (p value = 0.009). However, when examined by origin, cases of Southern European origin had an increased rs7665116 minor allele frequency (MAF), consistent with this being an ancestry-tagging SNP. The Southern European cases, despite similar mean CAG allele size, had a significantly older mean AO (p < 0.001), suggesting population-dependent phenotype stratification. When the generalized estimating equations models were adjusted for ancestry, the effect of the rs7665116 genotype on AO decreased dramatically. Our results do not support rs7665116 as a modifier of AO of motor symptoms, as we found evidence for a dramatic effect of phenotypic (AO) and genotypic (MAF) stratification among European cohorts that was not considered in previously reported association studies. A significantly older AO in Southern Europe may reflect population differences in genetic or environmental factors that warrant further investigation.
PMCID: PMC3492689  PMID: 22825315
19.  Neuropsychological profile of parkin mutation carriers with and without Parkinson disease: the CORE-PD study 
The cognitive profile of early onset Parkinson’s disease (EOPD) has not been clearly defined. Mutations in the parkin gene are the most common genetic risk factor for EOPD and may offer information about the neuropsychological pattern of performance in both symptomatic and asymptomatic mutation carriers.
EOPD probands and their first-degree relatives who did not have Parkinson’s disease (PD) were genotyped for mutations in the parkin gene and administered a comprehensive neuropsychological battery. Performance was compared between EOPD probands with (N=43) and without (N=52) parkin mutations. The same neuropsychological battery was administered to 217 first-degree relatives to assess neuropsychological function in individuals who carry parkin mutations but do not have PD.
No significant differences in neuropsychological test performance were found between parkin carrier and non-carrier probands. Performance also did not differ between EOPD non-carriers and carrier subgroups (i.e. heterozygotes, compound heterozygotes/homozygotes). Similarly, no differences were found among unaffected family members across genotypes. Mean neuropsychological test performance was within normal range in all probands and relatives.
Carriers of parkin mutations, whether or not they have PD, do not perform differently on neuropsychological measures as compared to non-carriers. The cognitive functioning of parkin carriers over time warrants further study.
PMCID: PMC3366462  PMID: 21092386
Parkinson’s disease; genetics; neuropsychological assessment; genotype; PARK2; parkin mutation
20.  Osteopontin enhances HIV replication and is increased in the brain and cerebrospinal fluid of HIV-infected individuals 
Journal of Neurovirology  2011;17(4):382-392.
Despite effective and widely available suppressive anti-HIV therapy, the prevalence of mild neurocognitive dysfunction continues to increase. HIV-associated neurocognitive disorder (HAND) is a multifactorial disease with sustained central nervous system inflammation and immune activation as prominent features. Inflammatory macrophages, HIV-infected and uninfected, play a central role in the development of HIV dementia. There is a critical need to identify biomarkers and to better understand the molecular mechanisms leading to cognitive dysfunction in HAND. In this regard, we identified through a subtractive hybridization strategy osteopontin (OPN, SPP1, gene) an inflammatory marker, as an upregulated gene in HIV-infected primary human monocyte-derived macrophages. Knockdown of OPN in primary macrophages resulted in a threefold decrease in HIV-1 replication. Ectopic expression of OPN in the TZM-bl cell line significantly enhanced HIV infectivity and replication. A significant increase in the degradation of the NF-κB inhibitor, IκBα and an increase in the nuclear-to-cytoplasmic ratio of NF-κB were found in HIV-infected cells expressing OPN compared to controls. Moreover, mutation of the NF-κB binding domain in the HIV-LTR abrogated enhanced promoter activity stimulated by OPN. Interestingly, compared to cerebrospinal fluid from normal and multiple sclerosis controls, OPN levels were significantly higher in HIV-infected individuals both with and without neurocognitive disorder. OPN levels were highest in HIV-infected individuals with moderate to severe cognitive impairment. Moreover, OPN was significantly elevated in brain tissue from HIV-infected individuals with cognitive disorder versus those without impairment. Collectively, these data suggest that OPN stimulates HIV-1 replication and that high levels of OPN are present in the CNS compartment of HIV-infected individuals, reflecting ongoing inflammatory processes at this site despite anti-HIV therapy.
PMCID: PMC3331788  PMID: 21556958
HIV-associated neurocognitive disorder; CD44; Nef
21.  A Genome-Wide Scan of Ashkenazi Jewish Crohn's Disease Suggests Novel Susceptibility Loci 
PLoS Genetics  2012;8(3):e1002559.
Crohn's disease (CD) is a complex disorder resulting from the interaction of intestinal microbiota with the host immune system in genetically susceptible individuals. The largest meta-analysis of genome-wide association to date identified 71 CD–susceptibility loci in individuals of European ancestry. An important epidemiological feature of CD is that it is 2–4 times more prevalent among individuals of Ashkenazi Jewish (AJ) descent compared to non-Jewish Europeans (NJ). To explore genetic variation associated with CD in AJs, we conducted a genome-wide association study (GWAS) by combining raw genotype data across 10 AJ cohorts consisting of 907 cases and 2,345 controls in the discovery stage, followed up by a replication study in 971 cases and 2,124 controls. We confirmed genome-wide significant associations of 9 known CD loci in AJs and replicated 3 additional loci with strong signal (p<5×10−6). Novel signals detected among AJs were mapped to chromosomes 5q21.1 (rs7705924, combined p = 2×10−8; combined odds ratio OR = 1.48), 2p15 (rs6545946, p = 7×10−9; OR = 1.16), 8q21.11 (rs12677663, p = 2×10−8; OR = 1.15), 10q26.3 (rs10734105, p = 3×10−8; OR = 1.27), and 11q12.1 (rs11229030, p = 8×10−9; OR = 1.15), implicating biologically plausible candidate genes, including RPL7, CPAMD8, PRG2, and PRG3. In all, the 16 replicated and newly discovered loci, in addition to the three coding NOD2 variants, accounted for 11.2% of the total genetic variance for CD risk in the AJ population. This study demonstrates the complementary value of genetic studies in the Ashkenazim.
Author Summary
Crohn's disease causes inflammation of the digestive tract resulting from the interaction of normal gut bacteria with the host immune system in genetically predisposed individuals. People of Jewish heritage have an increased risk of developing Crohn's disease compared to non-Jewish Europeans. So far, 71 genetic variants that increase the risk of Crohn's disease have been identified in individuals of European ancestry. Here, we take advantage of recent technical and methodological advances to explore Crohn's diseases-related genetic variants specific to the Ashkenazi Jewish population. We examined 6,347 individuals whose Jewish ancestry was confirmed by a large number of genetic markers and detected several variants associated with the increased risk of Crohn' disease. We confirmed the involvement of 12 known Crohn's disease risk variants in Ashkenazi Jews and identified novel genetic regions not previously found in non-Jewish European populations. Further studies of these regions may help discover biological pathways affecting susceptibility to Crohn's disease and lead to the development of novel treatments. This study also demonstrates the complementary value of genetic studies in isolated populations, like the Ashkenazim.
PMCID: PMC3297573  PMID: 22412388
22.  Clinical Correlates of Depressive Symptoms in Familial Parkinson's Disease 
Depression is one of the most common nonmotor complications of Parkinson's disease (PD) and has a major impact on quality of life. Although several clinical factors have been associated with depression in PD, the relationship between depression and stage of illness as well as between depression and degree of disability remains controversial. We have collected clinical data on 1,378 PD cases from 632 families, using the Unified Parkinson's Disease Rating Scale (UPDRS) Parts II (activities of daily living) & III (motor), the Mini-Mental State Exam, the Geriatric Depression Scale (GDS), and the Blessed Functional Activity Scale (Blessed). Analyses were performed using the 840 individuals with verified PD and without evidence of cognitive decline. Logistic regression was used to identify study variables that individually and collectively best predicted the presence of depressive symptoms (GDS ≥ 10). After correcting for multiple tests, depressive symptoms were significantly associated with Hoehn and Yahr stage and other clinical measures but not with any genetic variant (parkin, LRRK2, APOE). The Blessed score, education, presence of a first degree relative with signs of depression, and UPDRS Part II were found to best predict depressive symptomatology (R2 = 0.33; P = 4 × 10−48). Contrary to several reports, the results from this large study indicate that stage of illness, motor impairment, and functional disability are strongly correlated with depressive symptoms.
PMCID: PMC2872794  PMID: 18785635
Parkinson's disease; depression; Hoehn and Yahr stage; association; activities of daily living
23.  Multi-center analysis of glucocerebrosidase mutations in Parkinson disease 
The New England journal of medicine  2009;361(17):1651-1661.
Recent studies indicate an increased frequency of mutations in the gene for Gaucher disease, glucocerebrosidase (GBA), among patients with Parkinson disease. An international collaborative study was conducted to ascertain the frequency of GBA mutations in ethnically diverse patients with Parkinson disease.
Sixteen centers participated, including five from the Americas, six from Europe, two from Israel and three from Asia. Each received a standard DNA panel to compare genotyping results. Genotypes and phenotypic data from patients and controls were analyzed using multivariate logistic regression models and the Mantel Haenszel procedure to estimate odds ratios (ORs) across studies. The sample included 5691 patients (780 Ashkenazi Jews) and 4898 controls (387 Ashkenazi Jews).
All 16 centers could detect GBA mutations, L444P and N370S, and the two were found in 15.3% of Ashkenazi patients with Parkinson disease (ORs = 4.95 for L444P and 5.62 for N370S), and in 3.2% of non-Ashkenazi patients (ORs = 9.68 for L444P and 3.30 for N370S). GBA was sequenced in 1642 non-Ashkenazi subjects, yielding a frequency of 6.9% for all mutations, demonstrate that limited mutation screens miss half the mutant alleles. The presence of any GBA mutation was associated with an OR of 5.43 across studies. Clinically, although phenotypes varied, subjects with a GBA mutation presented earlier, and were more likely to have affected relatives and atypical manifestations.
Data collected from sixteen centers demonstrate that there is a strong association between GBA mutations and Parkinson disease.
PMCID: PMC2856322  PMID: 19846850
24.  Risk of Parkinson's Disease in Carriers of Parkin mutations: Estimation Using the Kin-Cohort Method 
Archives of neurology  2008;65(4):467-474.
To estimate the risk of Parkinson's disease in individuals with mutations in the Parkin gene.
We assessed point mutations and exon deletions and duplications in the Parkin gene in 247 PD probands with age at onset ≤50 and 104 control probands enrolled in the Genetic Epidemiology of PD study. For each first-degree relative, a consensus diagnosis of PD was established. The probability that each relative carried a mutation was estimated from the proband's Parkin carrier status using Mendelian principles and the relationship of the relative to the proband .
Parkin mutations were identified in 25 PD probands (10.1%), 72% of whom were heterozygotes. One Parkin homozygote reported 2 siblings with PD. The cumulative incidence of PD to age 65 in carrier relatives (age-specific penetrance) was estimated to be 7.0% (95% CI: 0.4-71.9%) compared to 1.7% (95% CI: 0.8-3.4%) in non-carrier relatives of cases (p=0.59) and 1.1% (95% CI: 0.3-3.4%), in relatives of controls ( compared to non-carriers p=0.52).
The cumulative risk of PD to age 65 in a non-carrier relative of a case with AAO ≤50 is not significantly greater than the general population risk among controls. Age specific penetrance among Parkin carriers, in particular heterozygotes, deserves further study.
PMCID: PMC2836931  PMID: 18413468
Parkin; Mutations; Parkinson's disease; Kin-cohort study; Early onset
25.  The impact of anxiety on conversion from mild cognitive impairment to Alzheimer’s disease 
To compare state and trait anxiety in mild cognitive impairment (MCI) patients and matched control subjects, and to assess the impact of these variables in predicting conversion to Alzheimer’s disease.
One hundred and forty-eight patients with MCI, broadly defined, were assessed and followed systematically. Baseline predictors for follow-up conversion to AD (entire sample: 39/148 converted to Alzheimer’s disease (AD)) included the Spielberger State-Trait Anxiety Inventory (STAI).
At baseline evaluation, MCI patients had higher levels of state and trait anxiety than controls, with no differences between future AD converters (n = 39) and non-converters. In age-stratified Cox proportional hazards model analyses, STAI State was not a significant predictor of conversion to AD (STAI State ≤30 vs. > 30 risk ratio, 1.68; 95% CI, 0.75, 3.77; p = 0.21), but higher Trait scores indicated a lower risk of conversion when STAI State, education, the Folstein Mini-Mental State Examination and HAM-D (depression score) were also included in the model (STAI Trait ≤30 vs. > 30 risk ratio, 0.36; 95% CI, 0.16, 0.82; p = 0.015).
In contrast to two other recent studies that showed anxiety predicted cognitive decline or conversion to AD, in this clinic-based sample, state anxiety was not a significant predictor. However, higher Trait anxiety predicted a lower risk of future conversion to AD. Further research with systematic long-term follow-up in larger samples is needed to clarify the role of state and trait anxiety in predicting MCI conversion to AD.
PMCID: PMC2787890  PMID: 19319929
mild cognitive impairment; Alzheimer’s disease; anxiety; depression

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