Gene family

A gene family is a set of several similar genes. They occur by the duplication of a single original gene. Usually they have similar biochemical functions. The idea that genes get duplicated is almost as old as the science of genetics.Taylor, John S. &  Raes, Jeroen 2004. Duplication and divergence: the evolution of new genes and old ideas. Annual Review of Genetics 38: 615-643.   

One such family are the genes for human haemoglobin subunits. The ten genes are in two clusters on different chromosomes, called the α-globin and β-globin loci.  These two gene clusters are thought to have arisen from a precursor gene being duplicated, about 500 million years ago. 

The biggest gene family is said to be the olfaction genes.Niimura Y. & Nei M. 2003. Evolution of olfactory receptor genes in the human genome. Proceedings of the National Academy of Sciences of the United States of America 100 (21): 12235–40.   The homeobox genes are another important group. Bürglin T.R. Affolter M. 2015. Homeodomain proteins: an update. Chromosoma, 1–25.  

Genes for the immune system include several gene families. They code for the major histocompatibility complex,Janeway CA Jr, Travers P, Walport M, et al. 2001. Immunobiology: The Immune System in health and disease. 5th edition. New York: Garland Science. The major histocompatibility complex and its functions.  and the immunoglobulins.Barclay A 2003. Membrane proteins with immunoglobulin-like domains--a master superfamily of interaction molecules. Seminars in Immunology 15 (4): 215–23.  The toll-like receptors are the main sensors of infection in mammals.

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Category:Genetics