Washington: A new study has revealed that as much as 30 percent of the large array of human olfactory receptor differs between any two individuals.
Researchers from the Monell Center and collaborating institutions suggested that this substantial variation is in turn reflected by variability in how each person perceives odours.
Humans have about 400 different types of specialized sensors, known as olfactory receptor proteins, that somehow work together to detect a large variety of odours.
To gain a better understanding of the extent of olfactory receptor variation and how this impacts human odour perception, Joel Mainland, PhD, a molecular biologist at Monell and his collaborators used a combination of high-throughput assays to measure how single receptors and individual humans respond to odours.
The researchers first cloned 511 known variants of human olfactory receptors and embedded them in host cells that are easy to grow in the laboratory. The next step was to measure whether each receptor variant responded to a panel of 73 different odour molecules. This process identified 28 receptor variants that responded to at least one of the odour molecules.
Drilling down, the researchers next examined the DNA of 16 olfactory receptor genes, discovering considerable variation within the genes for discrete receptors.
Using sophisticated mathematical modelling to extrapolate from these results, Mainland predicts that the olfactory receptors of any two individuals differ by about 30 percent.
This means that for any two randomly chosen individuals, approximately 140 of their 400 olfactory receptors will differ in how they respond to odour molecules.
The study was published in journal Nature Neuroscience.