Polymorphism of the ovine FOXP3 gene (FOXP3)

FOXP3 is a transcription factor predominantly expressed in CD4+ CD25+ thymocytes and CD4+ CD25+ peripheral T cells. It has been reported that variation in the FOXP3 gene (FOXP3) could cause impaired immune regulation. Using PCR-SSCP, variation in exon 4, exon 9–10 and exon 13–14 of ovine FOXP3, covering three functional domains (a proline rich domain, a leucine zipper-like motif and the forkhead domain, respectively) was investigated. Four SSCP banding patterns were observed for the exon 13–14 amplicon, while no variation was detected in either exon 4 or exon 9–10. Either one or two SSCP banding patterns were observed in the sheep studied. In accordance with the X chromosome location of FOXP3, ewes were homozygous or heterozygous, while rams were hemizygous. Sequencing of DNA corresponding to the four PCR-SSCP patterns for exon 13–14, revealed four unique DNA sequences which resulted from both sequence and length variation. These comprised of two SNPs (one in intron 13 and the other in exon 14), and variation in copy number for a hexa-nucleotide repeat (TGGCCC)n in intron 13. These results indicate that ovine FOXP3 is polymorphic and the variation detected in this region may have implications for immune regulation in sheep.