A Single IGF1 Allele Is a Major Determinant of Small Size in Dogs

National Human Genome Research Institute, Building 50, Room 5349, 50 South Drive MSC 8000, Bethesda, MD 20892-8000, USA.
Science (Impact Factor: 33.61). 05/2007; 316(5821):112-5. DOI: 10.1126/science.1137045
Source: PubMed


The domestic dog exhibits greater diversity in body size than any other terrestrial vertebrate. We used a strategy that exploits
the breed structure of dogs to investigate the genetic basis of size. First, through a genome-wide scan, we identified a major
quantitative trait locus (QTL) on chromosome 15 influencing size variation within a single breed. Second, we examined genetic
variation in the 15-megabase interval surrounding the QTL in small and giant breeds and found marked evidence for a selective
sweep spanning a single gene (IGF1), encoding insulin-like growth factor 1. A single IGF1 single-nucleotide polymorphism haplotype is common to all small breeds and nearly absent from giant breeds, suggesting that
the same causal sequence variant is a major contributor to body size in all small dogs.