Characterization of the porcine CDKN3 gene as a potential candidate for congenital splay leg in piglets

Congenital splay leg is a hereditary disease observed in newborn piglets. The etiology and pathogenetic mechanism of the disorder are still unknown. The gene for cyclin-dependent protein kinase inhibitor 3 (CDKN3) was identified as a potential candidate gene in a differential display experiment. We analyzed the gene on sequence variations and compared its expression in M. biceps femoris between healthy and affected piglets. Comparative sequencing of the coding region of three healthy and four splay leg piglets revealed twelve single nucleotide polymorphisms (SNP) resulting in six amino acid exchanges in the deduced sequences. However, all polymorphisms were observed in healthy as well as in splay leg piglets thus excluding structural differences of the gene as a cause of the disease. Besides full length transcripts, we found a variety of aberrantly transcribed cDNA in clones derived from M. biceps femoris of healthy as well as of splay leg piglets. All alternative transcripts coexist with normal cDNA. Expression analysis revealed a trend towards higher values in M. biceps femoris of splay leg piglets supporting the results obtained from a differential display.