Allelic variation in ovine fatty acid-binding protein (FABP4) gene

The fatty acid-binding protein 4 (FABP4) plays a role in lipid metabolism and has been implicated in intra-cellular lipid transport. While FABP4 variation has been reported in some species, variation in the coding sequence has not been reported in sheep. In this study two regions of ovine FABP4 were analysed using PCR-SSCP and sequencing. Five different PCR-SSCP patterns, representing five specific sequences (A ( 1 )-E ( 1 )) were detected in region 1 (exon 2-intron 2) with sequence analysis revealing three nucleotide substitutions and one deletion in the intron. In region 2 (exon 3-intron 3), four different PCR-SSCP patterns (A ( 2 )-D ( 2 )) were observed and four nucleotide substitutions were revealed. In total, fourteen haplotypes through both regions were defined. There was a difference (P < 0.001) in allele frequencies between two selection lines of Coopworth sheep that have been bred over many generations to be lean or fat. In region 1, A ( 1 ) and B ( 1 ) were most common (at a frequency of 50 and 30 % respectively) in the fat line, whereas these two variants were absent or rare in the lean line in which C ( 1 ) predominated (89 %). In region 2, C ( 2 ) was the most common variant (59 %) in the lean line but was absent in the fat line, whereas B ( 2 ) was predominant (83 %) in the fat line but was rare (3 %) in the lean line. These results indicate that ovine FABP4 is polymorphic and suggest further analysis is required to see if the variation detected affects fat deposition in sheep.