Genome-wide SNP scan of pooled DNA reveals nonsense mutation in <it>FGF20</it> in the scaleless line of featherless chickens

• Main Authors: Wells Kirsty L, Hadad Yair, Ben-Avraham Danny, Hillel Jossi, Cahaner Avigdor, Headon Denis J
• Format: Article
• Language: English
• Published: BMC 2012-06-01
• Series: BMC Genomics
• Online Access: http://www.biomedcentral.com/1471-2164/13/257

<p>Abstract</p> <p>Background</p> <p>Scaleless (<it>sc/sc</it>) chickens carry a single recessive mutation that causes a lack of almost all body feathers, as well as foot scales and spurs, due to a failure of skin patterning during embryogenesis. This spontaneous mutant line, first described in the 1950s, has been used extensively to explore the tissue interactions involved in ectodermal appendage formation in embryonic skin. Moreover, the trait is potentially useful in tropical agriculture due to the ability of featherless chickens to tolerate heat, which is at present a major constraint to efficient poultry meat production in hot climates. In the interests of enhancing our understanding of feather placode development, and to provide the poultry industry with a strategy to breed heat-tolerant meat-type chickens (broilers), we mapped and identified the <it>sc</it> mutation.</p> <p>Results</p> <p>Through a cost-effective and labour-efficient SNP array mapping approach using DNA from <it>sc/sc</it> and <it>sc/+</it> blood sample pools, we map the <it>sc</it> trait to chromosome 4 and show that a nonsense mutation in <it>FGF20</it> is completely associated with the <it>sc/sc</it> phenotype. This mutation, common to all <it>sc/sc</it> individuals and absent from wild type, is predicted to lead to loss of a highly conserved region of the FGF20 protein important for FGF signalling. <it>In situ</it> hybridisation and quantitative RT-PCR studies reveal that <it>FGF20</it> is epidermally expressed during the early stages of feather placode patterning. In addition, we describe a dCAPS genotyping assay based on the mutation, developed to facilitate discrimination between wild type and <it>sc</it> alleles.</p> <p>Conclusions</p> <p>This work represents the first loss of function genetic evidence supporting a role for FGF ligand signalling in feather development, and suggests FGF20 as a novel central player in the development of vertebrate skin appendages, including hair follicles and exocrine glands. In addition, this is to our knowledge the first report describing the use of the chicken SNP array to map genes based on genotyping of DNA samples from pooled whole blood. The identification of the <it>sc</it> mutation has important implications for the future breeding of this potentially useful trait for the poultry industry, and our genotyping assay can facilitate its rapid introgression into production lines.</p>