Or51b6, an olfactory receptor gene, is involved in the detection of chemical stimuli related to sensory perception of smell [4,5]. Olfactory receptor activity is part of the olfactory transduction pathway, which is crucial for the sense of smell and may also have implications in broader biological processes [5].

In genetic studies of Alzheimer's disease (AD), the performance decline of the immediate recall of the Rey-Osterrieth figure test in familial AD was associated with 122 genetic variants, among which Olfactory receptor OR51B6 showed the highest number of associated variants, and its expression was detected in temporal cortex neurons. Impaired olfactory function has been associated with cognitive impairment in AD, suggesting a potential role of OR51B6 in AD-related cognitive decline [1]. In β-thalassaemia carriers, the SNP rs5006884 in OR51B6 was associated with increased HbA2 levels, indicating its involvement in haemoglobin regulation [2]. In growth hormone-secreting pituitary adenomas, OR51B6 was up-regulated in the competing endogenous RNA network, potentially playing a role in the invasiveness of these adenomas [3]. In preeclampsia, OR51B6 was identified as a predictor of early-onset preeclampsia, and in a nasal epithelial Parkinson's disease (PD) cellular model, OR51B6 was down-regulated upon treatment with α-synuclein preformed fibrils [4,5].

In summary, Or51b6 is an olfactory receptor gene with potential functions in multiple disease conditions. Its associations with AD-related cognitive decline, haemoglobin regulation, pituitary adenoma invasiveness, preeclampsia prediction, and PD biomarker discovery highlight its importance in understanding these diseases. Although no gene knockout (KO) or conditional knockout (CKO) mouse models were mentioned in the provided references, the findings from these human-based studies suggest avenues for future in vivo functional studies using KO or CKO mouse models to further elucidate Or51b6's role in these biological processes and diseases.

References:

1. Sepulveda-Falla, Diego, Vélez, Jorge I, Acosta-Baena, Natalia, Mastronardi, Claudio A, Arcos-Burgos, Mauricio. 2024. Genetic modifiers of cognitive decline in PSEN1 E280A Alzheimer's disease. In Alzheimer's & dementia : the journal of the Alzheimer's Association, 20, 2873-2885. doi:10.1002/alz.13754. https://pubmed.ncbi.nlm.nih.gov/38450831/

2. Cyrus, Cyril, Vatte, Chittibabu, Chathoth, Shahanas, Alsaikhan, Jana, Al Ali, Amein K. 2019. Haemoglobin switching modulator SNPs rs5006884 is associated with increased HbA2 in β-thalassaemia carriers. In Archives of medical science : AMS, 17, 1064-1074. doi:10.5114/aoms.2019.86705. https://pubmed.ncbi.nlm.nih.gov/34336034/

3. Yin, H, Zheng, X, Tang, X, Yang, H, Li, S. 2021. Potential biomarkers and lncRNA-mRNA regulatory networks in invasive growth hormone-secreting pituitary adenomas. In Journal of endocrinological investigation, 44, 1947-1959. doi:10.1007/s40618-021-01510-x. https://pubmed.ncbi.nlm.nih.gov/33559847/

4. Hirata, Andréa Harumy de Lima, Camargo, Luiz Antônio de Jesus Rocha, Silva, Valdelena Alessandra da, Delle, Humberto, Camacho, Cleber P. 2023. Exploring the Potential of Olfactory Receptor Circulating RNA Measurement for Preeclampsia Prediction and Its Linkage to Mild Gestational Hypothyroidism. In International journal of molecular sciences, 24, . doi:10.3390/ijms242316681. https://pubmed.ncbi.nlm.nih.gov/38069004/

5. Kim, Hyojung, Kang, Seok-Jae, Jo, Young Mi, Cho, Seok Hyun, Lee, Yunjong. 2020. Novel Nasal Epithelial Cell Markers of Parkinson's Disease Identified Using Cells Treated with α-Synuclein Preformed Fibrils. In Journal of clinical medicine, 9, . doi:10.3390/jcm9072128. https://pubmed.ncbi.nlm.nih.gov/32640699/