Forkhead Box Protein N1 (FOXN1)

Mutations in the winged-helix transcription factor gene at the nude locus in mice and rats produce the pleiotropic phenotype of hairlessness and athymia, resulting in a severely compromised immune system. FOXN1 is orthologous to the mouse and rat genes and encodes a similar DNA-binding transcription factor that is thought to regulate keratin gene expression. A mutation in this gene has been correlated with T-cell immunodeficiency, the skin disorder congenital alopecia, and nail dystrophy. Alternative splicing in the 5' UTR of this gene has been observed.Mutations in winged-helix domain genes cause homeotic transformations in Drosophila and distort cell-fate decisions during vulval development in C. elegans. The whn gene was thus the first member of this class of genes to be implicated in a specific developmental defect in vertebrates.