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Article

Investigating Olfactory Gene Variation and Odour Identification in Older Adults

1
Centre for Healthy Brain Ageing, Faculty of Medicine, School of Psychiatry, University of New South Wales (UNSW), Sydney, NSW 2031, Australia
2
Department of Mathematics and Statistics, Curtin University, Perth, WA 6102, Australia
3
Queensland Brain Institute, University of Queensland, St. Lucia, QLD 4072, Australia
4
Centre for Advanced Imaging, University of Queensland, St. Lucia, QLD 4072, Australia
5
School of Medical Sciences, University of Sydney, Sydney, NSW 2006, Australia
6
Department of Developmental Disability Neuropsychiatry, UNSW, Sydney, NSW 2031, Australia
7
National Ageing Research Institute, Parkville, VIC 3052, Australia
8
Academic Unit for Psychiatry of Old Age, University of Melbourne, St George’s Hospital, Kew, Melbourne, VIC 3010, Australia
9
Neuroscience Research Australia, Sydney, NSW 2031, Australia
10
School of Medical Sciences, UNSW, Sydney, NSW 2031, Australia
11
Dementia Collaborative Research Centre Assessment and Better Care, UNSW, Sydney, NSW 2031, Australia
12
Neuropsychiatric Institute, the Prince of Wales Hospital, Sydney, NSW 2031, Australia
*
Author to whom correspondence should be addressed.
Received: 31 March 2021 / Revised: 27 April 2021 / Accepted: 27 April 2021 / Published: 29 April 2021
(This article belongs to the Special Issue Genetic and Environmental Factors in Ageing and Age-Related Disease)
Ageing is associated with a decrease in odour identification. Additionally, deficits in olfaction have been linked to age-related disease and mortality. Heritability studies suggest genetic variation contributes to olfactory identification. The olfactory receptor (OR) gene family is the largest in the human genome and responsible for overall odour identification. In this study, we sought to find olfactory gene family variants associated with individual and overall odour identification and to examine the relationships between polygenic risk scores (PRS) for olfactory-related phenotypes and olfaction. Participants were Caucasian older adults from the Sydney Memory and Ageing Study and the Older Australian Twins Study with genome-wide genotyping data (n = 1395, mean age = 75.52 ± 6.45). The Brief-Smell Identification Test (BSIT) was administered in both cohorts. PRS were calculated from independent GWAS summary statistics for Alzheimer’s disease (AD), white matter hyperintensities (WMH), Parkinson’s disease (PD), hippocampal volume and smoking. Associations with olfactory receptor genes (n = 967), previously identified candidate olfaction-related SNPs (n = 36) and different PRS with BSIT scores (total and individual smells) were examined. All of the relationships were analysed using generalised linear mixed models (GLMM), adjusted for age and sex. Genes with suggestive evidence for odour identification were found for 8 of the 12 BSIT items. Thirteen out of 36 candidate SNPs previously identified from the literature were suggestively associated with several individual BSIT items but not total score. PRS for smoking, WMH and PD were negatively associated with chocolate identification. This is the first study to conduct genetic analyses with individual odorant identification, which found suggestive olfactory-related genes and genetic variants for multiple individual BSIT odours. Replication in independent and larger cohorts is needed. View Full-Text
Keywords: olfaction; odour identification; genetics; ageing olfaction; odour identification; genetics; ageing
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MDPI and ACS Style

Raj, S.; Thalamuthu, A.; Armstrong, N.J.; Wright, M.J.; Kwok, J.B.; Trollor, J.N.; Ames, D.; Schofield, P.R.; Brodaty, H.; Sachdev, P.S.; Mather, K.A. Investigating Olfactory Gene Variation and Odour Identification in Older Adults. Genes 2021, 12, 669. https://0-doi-org.brum.beds.ac.uk/10.3390/genes12050669

AMA Style

Raj S, Thalamuthu A, Armstrong NJ, Wright MJ, Kwok JB, Trollor JN, Ames D, Schofield PR, Brodaty H, Sachdev PS, Mather KA. Investigating Olfactory Gene Variation and Odour Identification in Older Adults. Genes. 2021; 12(5):669. https://0-doi-org.brum.beds.ac.uk/10.3390/genes12050669

Chicago/Turabian Style

Raj, Siddharth, Anbupalam Thalamuthu, Nicola J. Armstrong, Margaret J. Wright, John B. Kwok, Julian N. Trollor, David Ames, Peter R. Schofield, Henry Brodaty, Perminder S. Sachdev, and Karen A. Mather 2021. "Investigating Olfactory Gene Variation and Odour Identification in Older Adults" Genes 12, no. 5: 669. https://0-doi-org.brum.beds.ac.uk/10.3390/genes12050669

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