Olfaction in Parkin single and compound heterozygotes in a cohort of young onset Parkinson's disease patients

Malek, N. et al. (2016) Olfaction in Parkin single and compound heterozygotes in a cohort of young onset Parkinson's disease patients. Acta Neurologica Scandinavica, 134(4), pp. 271-276. (doi: 10.1111/ane.12538) (PMID:26626018)

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Background: Parkin related Parkinson's disease (PD) is differentiated from idiopathic PD by absent or sparse Lewy bodies, and preserved olfaction. The significance of single Parkin mutations in the pathogenesis of PD is debated. Objectives: To assess olfaction results according to Parkin mutation status. To compare the prevalence of Parkin single heterozygous mutations in patients diagnosed with PD to the rate in healthy controls in order to establish whether these single mutations could be a risk factor for developing PD. Methods: Parkin gene mutation testing was performed in young onset PD (diagnosed <50 years old) to identify three groups: Parkin homozygous or compound heterozygote mutation carriers, Parkin single heterozygote mutation carriers, and non‐carriers of Parkin mutations. Olfaction was tested using the 40‐item British version of the University of Pennsylvania smell identification test (UPSIT). Results: Of 344 young onset PD cases tested, 8 (2.3%) were Parkin compound heterozygotes and 13 (3.8%) were Parkin single heterozygotes. Olfaction results were available in 282 cases (eight compound heterozygotes, nine single heterozygotes, and 265 non‐carriers). In Parkin compound heterozygotes, the median UPSIT score was 33, interquartile range (IQR) 28.5–36.5, which was significantly better than in single Parkin heterozygotes (median 19, IQR 18–28) and non‐carriers (median score 22, IQR 16–28) (ANOVA P < 0.001). These differences persisted after adjusting for age, disease duration, gender, and smoking (P < 0.001). There was no significant difference in UPSIT scores between single heterozygotes and non‐carriers (P = 0.90). Conclusions: Patients with Parkin compound heterozygous mutations have relatively preserved olfaction compared to Parkin single heterozygotes and non‐carriers. The prevalence of Parkin single heterozygosity is similar to the 3.7% rate reported in healthy controls.

Item Type:Articles
Additional Information:Funding Information: Parkinson's UK., National Institute for Health Research (NIHR) DeNDRoN network, NIHR Newcastle Biomedical Research Unit based at Newcastle upon Tyne Hospitals NHS Foundation Trust, Newcastle University, GE Healthcare, NIHR, Wellcome Trust, GlaxoSmithKline, Michael J Fox Foundation, Medical Research Council UK, Ipsen Fund, Motor Neuron Disease Association, Welsh Assembly Government, Teva, AbbVie, UCB, Boerhinger Ingelheim, GSK.
Glasgow Author(s) Enlighten ID:Grosset, Dr Donald and Grosset, Dr Katherine and Swallow, Dr Diane
Authors: Malek, N., Swallow, D.M.A., Grosset, K.A., Lawton, M.A., Smith, C.R., Bajaj, N.P., Barker, R.A., Ben-Shlomo, Y., Bresner, C., Burn, D.J., Foltynie, T., Morris, H.R., Williams, N., Wood, N.W., and Grosset, D.G.
College/School:College of Medical Veterinary and Life Sciences > Institute of Neuroscience and Psychology
Journal Name:Acta Neurologica Scandinavica
ISSN (Online):1600-0404
Published Online:01 December 2015
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