Sara Bech

Impact of dietary exposure to food contaminants on the risk of Parkinson's disease

This study aimed to investigate the association of Parkinsons disease (PD) with dietary exposure to polychlorinated biphenyls (PCBs) and methylmercury (MeHg) in a community with increased exposure levels. A total of 79 clinically verified idiopathic PD cases and 154 controls matched by sex and age were examined in this case-control study in the Faroe Islands. Blood and hair samples were collected and a questionnaire recorded lifetime information on residence, dietary habits, smoking history, and occupational exposure to solvents, pesticides, and metals. Both unconditional and conditional logistic regression analyses were used to estimate the odds ratio (OR) and 95% confidence interval (CI) in regard to relevant exposure variables. Increased ORs for dietary intakes of whale meat and blubber during adult life were statistically significant. The ORs for occupational exposure to solvents, pesticides and metals also suggested an increased risk for PD. Current serum concentrations of summation operator PCB and related contaminants suggested slightly increased ORs, although only beta-hexachlorocyclohexane (beta-HCH) was statistically significant. Increased intake of whale meat and blubber in adult life was significantly associated with PD, thus suggesting a positive association between previous exposure to marine food contaminants and development of PD.

Prevalence and incidence of Parkinson's disease in The Faroe Islands

Objective –  A study in The Faroe Islands in 1995 suggested a high prevalence of idiopathic Parkinson’s disease (IPD) and total parkinsonism of 187.6 and 233.4 per 100,000 inhabitants respectively.

Amyloid-related biomarkers and axonal damage proteins in parkinsonian syndromes

BACKGROUND Clinical differentiation between parkinsonian syndromes (PS) remains a challenge despite well-established clinical diagnostic criteria. Specific diagnostic biomarkers have yet to be identified, though in recent years, studies have been published on the aid of certain brain related proteins (BRP) in the diagnosing of PS. We investigated the levels of the light subunit of neurofilament triplet protein (NF-L), total tau and phosphorylated tau, amyloid-β(1-42), and the soluble α- and β-cleaved fragments of amyloid precursor proteins in a cohort of patients with various PS. METHODS Seventy-one patients with different PS and cerebellar disorders were included consecutively over 21 months. CSF was collected at inclusion. Clinical follow-up was performed after 16 months (median; range: 9-30). Statistical comparison was performed after follow-up on 53 patients in four subgroups of PS: multiple system atrophy (MSA)(n = 10), progressive supranuclear palsy (PSP)(n = 10), dementia with Lewy bodies (DLB)(n = 11), and Parkinsons disease (PD)(n = 22), using the non-parametric Kruskal-Wallis test. RESULTS A statistically significant difference was found for NF-L (p < 0.0001, lowest values for PD), Aβ(1-42,) (p = 0.002, lowest values for DLB), and sAPPα and sAPPβ (p = 0.03 and 0.02, lower values observed for DLB and MSA). CONCLUSION We demonstrate a potential role for sAPPα and sAPPβ in distinguishing between PS, a finding that needs to be confirmed in future studies of larger cohorts. There is a tendency towards low levels of Aβ(1-42) in DLB patients in our cohort. Further, our results support findings from previous studies, which indicate an ability to separate atypical PS from PD based on levels of NF-L.

The role of vitamin D levels and vitamin D receptor polymorphism on Parkinson's disease in the Faroe Islands

The role of vitamin D in Parkinsons disease (PD) has been proposed and both low serum 25-hydroxyvitamin D levels (25(OH)D) and vitamin D receptor polymorphisms (VDR) have been linked to PD. The aim of this study is to investigate the associations among 25(OH)D and three VDR polymorphisms and PD in the Faroese population where the prevalence of PD is high. We conducted a case-control study where 121 cases were studied for 25(OH)D levels and VDR polymorphisms against 235 randomly selected controls, matched by gender and age. No significant difference was observed in 25(OH)D levels between PD cases and controls (P=0.49), although cases had slightly lower values than controls. As well, no differences were found in genotype frequencies between cases and controls in the VDR polymorphisms studied (ApaI, BsmI, TaqI) (P=0.70, P=0.56 and P=0.54, respectively). However, we found that VDR ApaI/AC genotype was significantly associated with 25(OH)D levels (P=0.01). Although our results indicate no association between PD and vitamin D polymorphisms and/or 25(OH)D levels, the study cannot exclude a weak association. However, the known doubling in PD prevalence in the Faroe Islands cannot be explained by the polymorphisms examined in the VDR gene or the 25(OH)D levels and has to be explored further.

Huntington's disease-like and ataxia syndromes: Identification of a family with a de novo SCA17/TBP mutation

The autosomal dominant spinocerebellar ataxias, commonly referred to as SCAs, are clinically and genetically heterogeneous neurodegenerative disorders. Twenty-eight genetic subtypes have been identified, of which 7 are caused by expansion of a CAG trinucleotide repeat that encodes a polyglutamine tract in the respective proteins. SCA17 is caused by a CAG/CAA repeat expansion in the TATA box-binding protein-gene (TBP). In some cases the clinical phenotype of SCA17 overlaps that of Huntingtons disease (HD), hence the use of the term Huntingtons disease-like. We screened 89 patients with a Huntingtons disease-like phenotype without the HD-gene mutation and 178 patients with genetically unclassified cerebellar ataxia for the mutation in TBP. A 33-year old woman presenting with an HD like phenotype with a de novo 54 CAG/CAA repeat expansion was identified. Her normal allele included 38 repeats. The patients mother and father both carried normal range repeats, 38/38 and 33/39 respectively. Analysis of the repeat structures revealed that the expansion had occurred upon expansion of the longer paternal allele. We conclude that, however rare, SCA17 must be considered as a cause of Huntingtons disease-like phenotypes and ataxia syndromes, also in isolated cases.

Severe and rapidly progressing cognitive phenotype in a SCA17-family with only marginally expanded CAG/CAA repeats in the TATA-box binding protein gene: a case report.

BackgroundThe autosomal dominant spinocerebellar ataxias (SCAs) confine a group of rare and heterogeneous disorders, which present with progressive ataxia and numerous other features e.g. peripheral neuropathy, macular degeneration and cognitive impairment, and a subset of these disorders is caused by CAG-repeat expansions in their respective genes. The diagnosing of the SCAs is often difficult due to the phenotypic overlap among several of the subtypes and with other neurodegenerative disorders e.g. Huntington’s disease.Case presentationWe report a family in which the proband had rapidly progressing cognitive decline and only subtle cerebellar symptoms from age 42. Sequencing of the TATA-box binding protein gene revealed a modest elongation of the CAG/CAA-repeat of only two repeats above the non-pathogenic threshold of 41, confirming a diagnosis of SCA17. Normally, repeats within this range show reduced penetrance and result in a milder disease course with slower progression and later age of onset. Thus, this case presented with an unusual phenotype.ConclusionsThe current case highlights the diagnostic challenge of neurodegenerative disorders and the need for a thorough clinical and paraclinical examination of patients presenting with rapid cognitive decline to make a precise diagnosis on which further genetic counseling and initiation of treatment modalities can be based.

Familial aggregation of Parkinson's disease in the Faroe Islands

The Faroe Islands are a geographic population isolated in the North Atlantic with a high prevalence of Parkinsons disease (PD). Although environmental risk factors are well described, the familial aggregation of PD on the Islands has yet to be explored. Complete ascertainment of all patients with PD was performed, including 217 cases and 251 control subjects. All patients were neurologically assessed and diagnosed using UK Brain Bank criteria and Hohn and Yahr staging. Comprehensive genealogical and detailed cartographic analyses were performed. Relative risk and risk ratios were calculated with respect to the general population. Patients with PD in the Faroes have a higher age at symptom onset and diagnosis than for neighboring countries. Clinically, patients are similar; however, they are more likely to have affected relatives than randomly selected control subjects, matched by sex and age. Disease is most prevalent within two geographic regions. Overall, the relative risk for PD was 2.3 (95% confidence interval [CI], 1.2‐4.3; P = 0.008) for siblings and 1.4 (95% CI, 1.01‐1.99, P = 0.04) for first cousins. The etiology and excess prevalence of PD on the Faroes is complicated. Regional and familial clustering, and subsequent segregation analysis, suggests the disease best fits a genetic etiology with limited support for an environmental contribution. Pedigree‐based analysis of PD on the Faroe Islands which has few founders and a relatively homogeneous background may elaborate on these possibilities and their joint contribution.

The influence of preanalytical conditions on the DJ-1 concentration in human cerebrospinal fluid

AIM The purpose of this study was to establish the influence of centrifugation and protease activity on the cerebrospinal fluid (CSF) concentrations of DJ-1 and hemoglobin. MATERIALS & METHODS The concentrations of DJ-1 and hemoglobin were determined in 12 (DJ-1) and six (hemoglobin) pairs of CSF samples, with one sample being stored without centrifugation and the other being centrifuged at 2000 × g before storage. The DJ-1 concentration was also determined in centrifuged and uncentrifuged CSF containing protease inhibitors and compared with values determined in centrifuged and uncentrifuged CSF samples without protease inhibitors. Furthermore, specific protein concentrations were determined in CSF from two groups, each comprising 23 patients with Parkinsons disease. In one group the CSF was centrifuged at 1300-1800 × g, 4°C, 10 min, and in the other at 2000 × g, 4°C, 10 min. RESULTS Centrifugation at 2000 × g resulted in significantly lower CSF DJ-1 concentrations compared with no centrifugation and centrifugation at a lower g-force. There was a significant difference in the hemoglobin concentration between centrifuged and uncentrifuged CSF. In all centrifuged samples the hemoglobin concentration was <200 ng/ml including blood contaminated samples centrifuged at 2000 × g. When a protease inhibitor cocktail was added to the CSF prior to centrifugation, the DJ-1 concentration was significantly higher. CONCLUSION Preanalytical factors such as centrifugation and protease inhibition must be carefully controlled when handling CSF for analysis of DJ-1 and other biomarkers, as DJ-1 was influenced by blood contamination, centrifugation and protease activity.

Parkinson's disease, genetic variability and the Faroe Islands

INTRODUCTION The Faroe Islands is a geographically isolated population in the North Atlantic with a high prevalence of Parkinson disease (PD). The disease etiology is still unknown, although dietary pollutants are considered a risk factor. The genetic risk underlying disease susceptibility has yet to be elucidated. METHODS Sequence analysis was performed in genes previously linked with PD in 91 patients and 96 healthy control subjects. RESULTS Fourteen missense mutations, of which one was novel, were identified in six genes. One patient (1%) did carry the known pathogenic mutation LRRK2 p.G2019S mutation, 19 patients (22%) did carry mutations of unknown significance while 70 patients (78.0%) did not have any identifiable genetic risk. A total of 14 controls (14.6%) carried mutations of unknown significance. CONCLUSION This study suggests that rare variants in genes previously linked to PD are not major contributors to PD in the Faroe Islands. Further exome sequencing and comparative analyses within and among well-described pedigrees with multi-incident PD are now warranted.

Carnitine levels and mutations in the SLC22A5 gene in Faroes patients with Parkinson’s disease

INTRODUCTION Mitochondrial dysfunction, oxidative stress and energy production have been implicated in the etiology of Parkinsons disease (PD). Several agents are under investigation for potential neuroprotective effects including acetyl-l-carnitine (ALC). OBJECTIVE To investigate whether low carnitine levels and mutations in the SLC22A5 gene encoding the carnitine transporter are associates with PD risk in the Faroe Islands where the prevalence of both PD and carnitine transporter deficiency (CTD) is high. METHODS We conducted a case-control study with 121 cases and 235 randomly selected controls, matched by gender and age. Blood spots were analyzed for free and total carnitine levels by QUATTRO LC triple quadrupole mass spectrometry (MS/MS) and sequencing performed for five genetic mutations in the SLC22A5 gene with ABI PRISM 3130. RESULTS PD cases had significantly lower levels of free and total carnitine levels compared with controls (P < .001). However, stratifying according to mutation status, the lower levels of carnitine was only evident among the non-mutation carriers. Specifically, no difference was found in c.95A > G mutation frequency in the SLC22A5 gene among cases and controls (p = .70). CONCLUSION Low carnitine levels seem to be associated with PD, but only in individuals without the c.95A > G mutation rendering the carnitine transporter less efficient. Thus, the difference in carnitine levels is not caused by a higher frequency of c.95A > G mutation carriers in cases. The cause may be dietary or due to different gut microbiota among cases.