A regulatory mutation in IGF2 causes a major QTL effect on muscle growth in the pig.
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Most traits and disorders have a multifactorial background indicating that they are controlled by environmental factors as well as an unknown number of quantitative trait loci (QTLs). The identification of mutations underlying QTLs is a challenge because each locus explains only a fraction of the phenotypic variation. A paternally expressed QTL affecting muscle growth, fat deposition and size of the heart in pigs maps to the IGF2 (insulin-like growth factor 2) region. Here we show that this QTL is caused by a nucleotide substitution in intron 3 of IGF2. The mutation occurs in an evolutionarily conserved CpG island that is hypomethylated in skeletal muscle. The mutation abrogates in vitro interaction with a nuclear factor, probably a repressor, and pigs inheriting the mutation from their sire have a threefold increase in IGF2 messenger RNA expression in postnatal muscle. Our study establishes a causal relationship between a single-base-pair substitution in a non-coding region and a QTL effect. The result supports the long-held view that regulatory mutations are important for controlling phenotypic variation.
author list (cited authors)
Van Laere, A., Nguyen, M., Braunschweig, M., Nezer, C., Collette, C., Moreau, L., ... Andersson, L.
complete list of authors
Van Laere, Anne-Sophie||Nguyen, Minh||Braunschweig, Martin||Nezer, Carine||Collette, Catherine||Moreau, Laurence||Archibald, Alan L||Haley, Chris S||Buys, Nadine||Tally, Michael||Andersson, Göran||Georges, Michel||Andersson, Leif