How many genes comprise the odor receptor gene family?

How many genes comprise the odor receptor gene family?

• A. 2,000 genes
• B. 1,000 genes (only ~350 are active) - represents about 1% of all our genes
• C. 100 genes
• D. 10,000 genes

Answer: (B)

Odor detection relies on a very large gene family of odorant receptors in the genome. In humans this family comprises about a thousand gene loci, spread across the genome. Of these, only a subset are actually functional and expressed in olfactory neurons—roughly 350 receptor genes are active, while the rest are pseudogenes due to mutations. So the family as a whole includes around 1,000 gene sequences, with about 350 contributing to odor detection in most individuals. This large, mostly nonfunctional reservoir explains why we have a broad but finite set of receptors: the active receptors are what enable us to discriminate many different smells, while the many extra loci represent historical duplications and nonfunctional copies.

Odor detection relies on a very large gene family of odorant receptors in the genome. In humans this family comprises about a thousand gene loci, spread across the genome. Of these, only a subset are actually functional and expressed in olfactory neurons—roughly 350 receptor genes are active, while the rest are pseudogenes due to mutations. So the family as a whole includes around 1,000 gene sequences, with about 350 contributing to odor detection in most individuals. This large, mostly nonfunctional reservoir explains why we have a broad but finite set of receptors: the active receptors are what enable us to discriminate many different smells, while the many extra loci represent historical duplications and nonfunctional copies.