Association between olfactory receptor genes, eating behavior traits and adiposity: Results from the Quebec Family Study
ABSTRACT Obesity is a major health problem that can be influenced by eating behaviors. Evidence suggests that the sensory properties of food influence eating behaviors and lead to overeating and overweight. A previous genome-wide linkage scan for eating behavior traits assessed with the Three-Factor Eating Questionnaire (cognitive dietary restraint, disinhibition and hunger) performed in the Quebec Family Study (QFS) revealed a quantitative trait locus for disinhibition on chromosome 19p13. This region encodes a cluster of seven olfactory receptor (OR) genes, including OR7D4, previously associated with odor perceptions. Direct sequencing of the OR7D4 gene revealed 16 sequence variants. Nine OR7D4 sequence variants with minor allele frequency (MAF)>1% as well as 100 SNPs spanning the cluster of OR genes on 19p13 were tested for association with age- and sex-adjusted eating behaviors as well as adiposity traits in 890 subjects. One OR7D4 sequence variant (rs2878329 G>A) showed evidence of association with reduced levels of adiposity (p=0.03), cognitive dietary restraint (p=0.05) and susceptibility to hunger (p=0.008). None of the OR7D4 SNPs was associated with disinhibition, but a SNP (rs2240927) in another OR gene (OR7E24) showed evidence of association (p=0.03). Another SNP in the OR7G3 gene (rs10414255) was also found to be associated with adiposity and eating behaviors. These results are the first to suggest that variations in human olfactory receptor genes can influence eating behaviors and adiposity. The associations reported in the present study should be interpreted with caution considering the number of tests performed and considered as potential new hypotheses about the effects OR polymorphisms on eating behaviors and obesity that need to be further explored in other populations.
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ABSTRACT: Olfactory cues directly link the environment to gene expression. Two types of olfactory cues, food odors and social odors, alter genetically predisposed hormone-mediated activity in the mammalian brain. The honeybee is a model organism for understanding the epigenetic link from food odors and social odors to neural networks of the mammalian brain, which ultimately determine human behavior. Pertinent aspects that extend the honeybee model to human behavior include bottom-up followed by top-down gene, cell, tissue, organ, organ-system, and organism reciprocity; neurophysiological effects of food odors and of sexually dimorphic, species-specific social odors; a model of motor function required for social selection that precedes sexual selection; and hormonal effects that link current neuroscience to social science affects on the development of animal behavior. As the psychological influence of food odors and social orders is examined in detail, the socioaffective nature of olfactory cues on the biologically based development of sexual preferences across all species that sexually reproduce becomes clearer.03/2012; 2:17338. DOI:10.3402/snp.v2i0.17338
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ABSTRACT: Carcass fatness is an important trait in most pig breeding programs. Following market requests, breeding plans for fresh pork consumption are usually designed to reduce carcass fat content and increase lean meat deposition. However, the Italian pig industry is mainly devoted to the production of Protected Designation of Origin dry cured hams: pigs are slaughtered at around 160 kg of live weight and the breeding goal aims at maintaining fat coverage, measured as backfat thickness to avoid excessive desiccation of the hams. This objective has shaped the genetic pool of Italian heavy pig breeds for a few decades. In this study we applied a selective genotyping approach within a population of ~ 12,000 performance tested Italian Large White pigs. Within this population, we selectively genotyped 304 pigs with extreme and divergent backfat thickness estimated breeding value by the Illumina PorcineSNP60 BeadChip and performed a genome wide association study to identify loci associated to this trait. We identified 4 single nucleotide polymorphisms with P≤5.0E-07 and additional 119 ones with 5.0E-07<P≤5.0E-05. These markers were located throughout all chromosomes. The largest numbers were found on porcine chromosomes 6 and 9 (n=15), 4 (n=13), and 7 (n=12) while the most significant marker was located on chromosome 18. Twenty-two single nucleotide polymorphisms were in intronic regions of genes already recognized by the Pre-Ensembl Sscrofa10.2 assembly. Gene Ontology analysis indicated an enrichment of Gene Ontology terms associated with nervous system development and regulation in concordance with results of large genome wide association studies for human obesity. Further investigations are needed to evaluate the effects of the identified single nucleotide polymorphisms associated with backfat thickness on other traits as a pre-requisite for practical applications in breeding programs. Reported results could improve our understanding of the biology of fat metabolism and deposition that could also be relevant for other mammalian species including humans, confirming the role of neuronal genes on obesity.BMC Genomics 11/2012; 13:583. DOI:10.1186/1471-2164-13-583 · 4.04 Impact Factor
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ABSTRACT: Olfactory receptor (OR) expression is also present in the sperm cells and could mediate sperm chemotaxis. OR1D2 was the first OR expressed in the testis demonstrated to be involved in chemotaxis and to be expressed also in the nose with a similar behavior. Bourgeonal is the OR1D2 most potent known agonist. Infertility affects ~15 % of couples in western countries and sometimes it is unexplained. This pilot study compared the bourgeonal olfactory thresholds, the ability of sperm to sense the bourgeonal and the frequency of 13 single nucleotide polymorphisms (SNPs) of OR1D2 gene in nine males suffering of unexplained infertility with a control group of 15 healthy males. The mean olfactory threshold for bourgeonal was statistically different between the study group (10.5 ± 3.7; median 12.3) and the control group (14.0 ± 2.8; median 15.5) (p = 0.006). Statistical analysis showed a significantly higher percentage of spermatozoa that migrated toward the capillaries filled with bourgeonal in the control group compared to the study group (p < 0.0001). Sperm migration was equally inhibited in both groups of subjects when, together with bourgeonal, capillaries were filled with undecanal, a strong bourgeonal inhibitor (p = 0.42). The 13 SNPs of OR1D2 revealed a statistically significant difference for allele and genotype frequency of rs769423 in study group versus control group (p = 0.02). The present preliminary study seems to confirm the important role of OR1D2 both in nose and spermatozoa and may explain the idiopathic infertility of the study group. Further studies on larger series are mandatory to confirm our preliminary evidence.European archives of oto-rhino-laryngology. Supplement 03/2013; DOI:10.1007/s00405-013-2441-0