The chicken frizzle feather is due to an a-keratin (KRT75) mutation that causes a defective rachis

Authors: NG, CHEN SIANG - Academia Sinica; WU, PING - University Of Southern California; FOLEY, JOHN - Indiana University School Of Medicine; FOLEY, ANNE - Indiana University School Of Medicine; MCDONALD, MERRY - Baylor College Of Medicine; JUAN, WEN-TAU - Academia Sinica; HUANG, CHIH-JEN - Academia Sinica; LAI, YU-TING - Academia Sinica; LO, WEN-SUI - Academia Sinica; CHEN, CHIH-FENG - National Chung-Hsing University; LEAL, SUZANNE - Indiana University School Of Medicine; Zhang, Huanmin; WIDELITZ, RANDALL - University Of Southern California; PATEL, PRAGNA - University Of Southern California; LI, WEN-HSIUNG - Academia Sinica; CHUONG, CHENG-MING - University Of Southern California

Submitted to: PLoS Genetics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/19/2012
Publication Date: 7/19/2012
Citation: Ng, C., Wu, P., Foley, J., Foley, A., McDonald, M., Juan, W., Huang, C., Lai, Y., Lo, W., Chen, C., Leal, S.M., Zhang, H., Widelitz, R.B., Patel, P.I., Li, W., Chuong, C. 2012. The chicken frizzle feather is due to an a-keratin (KRT75) mutation that causes a defective rachis. PLoS Genetics. 8(7). Available: http://www.plosgenetics.org/article/info%3Adoi%2F10.1371%2Fjournal.pgen.1002748.

Interpretive Summary: Chicken feathers are of complex forms and have served as a model for study of developmental and evolutionary morphology in birds. By evaluation of the whole genome DNA polymorphism of the chickens with or without a specific form of feather, known as the frizzle feather, followed by DNA sequence examination, a functional gene was identified that is responsible for the frizzle feather. This study demonstrated the potential of this research approach in identifying functional genes underlying of phenotypic traits of interests.

Technical Abstract: Feathers have complex forms and are an excellent model to study the development and evolution of morphologies. Existing chicken feather mutants are especially useful for identifying genetic determinants of feather formation. The present study focused on the gene, F, underlying the frizzle feather trait that has a characteristic curled feather rachis and barbs in domestic chickens. Our developmental biology studies identified defects in feather medulla formation and physical studies revealed that the frizzle feather curls in a stepwise manner. The frizzle gene is transmitted in an autosomal incomplete dominant mode. A whole genome linkage scan of five pedigrees with 2678 SNPs revealed association of the frizzle locus with a keratin gene-enriched region within the linkage group E22C19W28_E50C23. Sequence analyses of the keratin gene cluster identified a 69 bp in-frame deletion in a conserved region of KRT75, an alpha-keratin protein. Retroviral-mediated expression of the mutated F cDNA in the wild-type rectrix qualitatively changed the bending of the rachis with some features of frizzle feathers including irregular kinks, severe bending near their distal ends, and substantially higher variations among samples in comparison to normal feathers. These results confirmed KRT75 as the F gene. This study demonstrates the potential of our approach for identifying genetic determinants of feather forms.