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- Mattsson, Niklas, 1979, et al.
(författare)
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CSF biomarker variability in the Alzheimer's Association quality control program
- 2013
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Ingår i: Alzheimers & Dementia. - : Wiley. - 1552-5260 .- 1552-5279. ; 9:3, s. 251-261
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Tidskriftsartikel (refereegranskat)abstract
- Background The cerebrospinal fluid (CSF) biomarkers amyloid beta 1–42, total tau, and phosphorylated tau are used increasingly for Alzheimer's disease (AD) research and patient management. However, there are large variations in biomarker measurements among and within laboratories. Methods Data from the first nine rounds of the Alzheimer's Association quality control program was used to define the extent and sources of analytical variability. In each round, three CSF samples prepared at the Clinical Neurochemistry Laboratory (Mölndal, Sweden) were analyzed by single-analyte enzyme-linked immunosorbent assay (ELISA), a multiplexing xMAP assay, or an immunoassay with electrochemoluminescence detection. Results A total of 84 laboratories participated. Coefficients of variation (CVs) between laboratories were around 20% to 30%; within-run CVs, less than 5% to 10%; and longitudinal within-laboratory CVs, 5% to 19%. Interestingly, longitudinal within-laboratory CV differed between biomarkers at individual laboratories, suggesting that a component of it was assay dependent. Variability between kit lots and between laboratories both had a major influence on amyloid beta 1–42 measurements, but for total tau and phosphorylated tau, between-kit lot effects were much less than between-laboratory effects. Despite the measurement variability, the between-laboratory consistency in classification of samples (using prehoc-derived cutoffs for AD) was high (>90% in 15 of 18 samples for ELISA and in 12 of 18 samples for xMAP). Conclusions The overall variability remains too high to allow assignment of universal biomarker cutoff values for a specific intended use. Each laboratory must ensure longitudinal stability in its measurements and use internally qualified cutoff levels. Further standardization of laboratory procedures and improvement of kit performance will likely increase the usefulness of CSF AD biomarkers for researchers and clinicians.
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| 2. |
- Jezierska, Justyna, et al.
(författare)
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Identification and characterization of novel PDYN mutations in dominant cerebellar ataxia cases.
- 2013
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Ingår i: Journal of Neurology. - : Springer Science and Business Media LLC. - 0340-5354 .- 1432-1459. ; 260:7, s. 1807-1812
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Tidskriftsartikel (refereegranskat)abstract
- We have recently identified missense mutations in prodynorphin (PDYN), the precursor to dynorphin opioid peptides, as the cause for spinocerebellar ataxia (SCA23) in Dutch ataxia cases. We report a screen of PDYN for mutations in 371 cerebellar ataxia cases, which had a positive family history; most are of French origin. Sequencing revealed three novel putative missense mutations and one heterozygous two-base pair deletion in four independent SCA patients. These variants were absent in 400 matched controls and are located in the highly conserved dynorphin domain. To resolve the pathogenicity of the heterozygous variants, we assessed the peptide production of the mutant PDYN proteins. Two missense mutations raised dynorphin peptide levels, the two-base pair deletion terminated dynorphin synthesis, and one missense mutation did not affect PDYN processing. Given the outcome of our functional analysis, we may have identified at least two novel PDYN mutations in a French and a Moroccan SCA patient. Our data corroborates recent work that also showed that PDYN mutations only account for a small percentage (~0.1 %) of European SCA cases.
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| 4. |
- Ramakers, I. H. G. B., et al.
(författare)
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Anxiety is related to Alzheimer cerebrospinal fluid markers in subjects with mild cognitive impairment
- 2013
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Ingår i: Psychological Medicine. - 0033-2917 .- 1469-8978. ; 43:5, s. 911-920
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Tidskriftsartikel (refereegranskat)abstract
- Background Anxiety, apathy and depression are common in subjects with mild cognitive impairment (MCI) and may herald Alzheimer's disease (AD). We investigated whether these symptoms correlated with cerebrospinal fluid (CSF) markers for AD in subjects with MCI. Method Subjects with MCI (n=268) were selected from the 'Development of screening guidelines and criteria for pre-dementia Alzheimer's disease' (DESCRIPA) and Alzheimer's Disease Neuroimaging Initiative (ADNI) studies. We measured amyloid β(1-42) protein (Aβ42) and total tau (t-tau) in CSF. Neuropsychiatric symptoms were measured with the Neuropsychiatric Inventory. Results Depressive symptoms were reported by 55 subjects (21%), anxiety by 35 subjects (13%) and apathy by 49 subjects (18%). The presence of anxiety was associated with abnormal CSF Aβ42 [odds ratio (OR) 2.3, 95% confidence interval (CI) 1.6-3.3] and t-tau (OR 2.6, 95% CI 1.9-3.6) concentrations and with the combination of abnormal concentrations of both Aβ42 and t-tau (OR 3.1, 95% CI 2.0-4.7). The presence of agitation and irritability was associated with abnormal concentrations of Aβ42 (agitation: OR 1.6, 95% CI 1.1-2.3; irritability: OR 2.2, 95% CI 1.5-3.3). Symptoms of depression and apathy were not related to any of the CSF markers. Conclusions In subjects with MCI, symptoms of anxiety, agitation and irritability may reflect underlying AD pathology, whereas symptoms of depression and apathy do not. © 2012 Cambridge University Press.
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