Abstract

Lipoprotein Lipase (LPL) is a key enzyme in lipid transport. It catalyses the hydrolysis of the triacylglycerol component of chylomicrons and very low-density lipoproteins (VLDL), providing non-esterified fatty acids for tissue utilization. The gene encoding for LPL has already been identified in several species except the dog. Mutations of the human LPL-gene have been shown to cause partial or complete malfunction of the enzyme, resulting in accumulation of lipoproteins in the blood. This condition is called familial LPL deficiency. LPL malfunction results in hyperlipoproteinemia, recurrent acute pancreatitis, and ultimately pancreatic insufficiency. Several authors have postulated a genetic cause for pancreatitis in the Miniature Schnauzer. An idiopathic increase in serum triglyceride concentration can also be found in this breed. Based on these findings we were evaluating a possible role of the lipoprotein lipase gene in the development of pancreatitis and hyperlipidemia in the Miniature Schnauzer. First, we identified the genetic sequence of the LPL gene in the dog. We determined clones on the Trace Archive database for the canine genome project that contain the genomic sequence of a particular exon as well as its adjacent intronic regions. Based on these findings we designed primers for each exon using the software Netprimer (www.premierbiosoft.com/netprimer/index.html). Canine subjects were chosen from a pool of 170 Miniature Schnauzers from the database at the Gastrointestinal Laboratory at Texas A&M University. Based on clinical history, serum cPLI concentrations, and serum triglyceride concentrations 21 Miniature Schnauzers were chosen and were selected into a clinically normal control group (9 dogs) and an affected group (12 dogs). DNA was then collected from either white blood cells or mucosal cells of these dogs. After PCR optimization, exon 1 through 9 including the adjacent intronic regions were amplified in all dogs using MasterAmp Extra – Long PCR Kit (Epicentre, WI, USA) and were sequenced in triplicates. Differences in the nucleotide sequences were then compared among the two groups. 10 exonic SNPs and 9 intronic SNPs were identified. Upon analysis, none of these variations could be associated with the disease status. We conclude that pancreatitis associated with hyperlipidemia in the Miniature Schnauzer is not linked to mutations of the lipoprotein lipase gene or its splicing regions.