@article{KuzkinaBargarSchmittetal.2021,
  author    = {Kuzkina, Anastasia and Bargar, Connor and Schmitt, Daniela and R{\"o}ßle, Jonas and Wang, Wen and Schubert, Anna-Lena and Tatsuoka, Curtis and Gunzler, Steven A. and Zou, Wen-Quan and Volkmann, Jens and Sommer, Claudia and Doppler, Kathrin and Chen, Shu G.},
  title     = {Diagnostic value of skin RT-QuIC in Parkinson's disease: a two-laboratory study},
  series = {NPJ Parkinson's Disease},
  volume    = {7},
  journal   = {NPJ Parkinson's Disease},
  number    = {1},
  doi       = {10.1038/s41531-021-00242-2},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-260451},
  year      = {2021},
  abstract  = {Skin alpha-synuclein deposition is considered a potential biomarker for Parkinson's disease (PD). Real-time quaking-induced conversion (RT-QuIC) is a novel, ultrasensitive, and efficient seeding assay that enables the detection of minute amounts of alpha-synuclein aggregates. We aimed to determine the diagnostic accuracy, reliability, and reproducibility of alpha-synuclein RT-QuIC assay of skin biopsy for diagnosing PD and to explore its correlation with clinical markers of PD in a two-center inter-laboratory comparison study. Patients with clinically diagnosed PD (n = 34), as well as control subjects (n = 30), underwent skin punch biopsy at multiple sites (neck, lower back, thigh, and lower leg). The skin biopsy samples (198 in total) were divided in half to be analyzed by RT-QuIC assay in two independent laboratories. The a-synuclein RT-QuIC assay of multiple skin biopsies supported the clinical diagnosis of PD with a diagnostic accuracy of 88.9\% and showed a high degree of inter-rater agreement between the two laboratories (92.2\%). Higher alpha-synuclein seeding activity in RT-QuIC was shown in patients with longer disease duration and more advanced disease stage and correlated with the presence of REM sleep behavior disorder, cognitive impairment, and constipation. The alpha-synuclein RT-QuIC assay of minimally invasive skin punch biopsy is a reliable and reproducible biomarker for Parkinson's disease. Moreover, alpha-synuclein RT-QuIC seeding activity in the skin may serve as a potential indicator of progression as it correlates with the disease stage and certain non-motor symptoms.},
  language  = {en}
}
@article{KuzkinaRoessleSegeretal.2023,
  author    = {Kuzkina, A. and R{\"o}ßle, J. and Seger, A. and Panzer, C. and Kohl, A. and Maltese, V. and Musacchio, T. and Blaschke, S. J. and Tamg{\"u}ney, G. and Kaulitz, S. and Rak, K. and Scherzad, A. and Zimmermann, P. H. and Klussmann, J. P. and Hackenberg, S. and Volkmann, J. and Sommer, C. and Sommerauer, M. and Doppler, K.},
  title     = {Combining skin and olfactory α-synuclein seed amplification assays (SAA)—towards biomarker-driven phenotyping in synucleinopathies},
  series = {npj Parkinson's Disease},
  volume    = {9},
  journal   = {npj Parkinson's Disease},
  issn      = {2373-8057},
  doi       = {10.1038/s41531-023-00519-8},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-357687},
  year      = {2023},
  abstract  = {Seed amplification assays (SAA) are becoming commonly used in synucleinopathies to detect α-synuclein aggregates. Studies in Parkinson's disease (PD) and isolated REM-sleep behavior disorder (iRBD) have shown a considerably lower sensitivity in the olfactory epithelium than in CSF or skin. To get an insight into α-synuclein (α-syn) distribution within the nervous system and reasons for low sensitivity, we compared SAA assessment of nasal brushings and skin biopsies in PD (n = 27) and iRBD patients (n = 18) and unaffected controls (n = 30). α-syn misfolding was overall found less commonly in the olfactory epithelium than in the skin, which could be partially explained by the nasal brushing matrix exerting an inhibitory effect on aggregation. Importantly, the α-syn distribution was not uniform: there was a higher deposition of misfolded α-syn across all sampled tissues in the iRBD cohort compared to PD (supporting the notion of RBD as a marker of a more malignant subtype of synucleinopathy) and in a subgroup of PD patients, misfolded α-syn was detectable only in the olfactory epithelium, suggestive of the recently proposed brain-first PD subtype. Assaying α-syn of diverse origins, such as olfactory (part of the central nervous system) and skin (peripheral nervous system), could increase diagnostic accuracy and allow better stratification of patients.},
  language  = {en}
}