IDENTIFYING QUANTITATIVE TRAIT LOCI EFFECTING LIVER WEIGHT IN SM/J X LG/J MICE. Saranya Bala1, Jim Cheverud2, Gloria Fawcett2, Jane P. Kenney-Hunt2, Biology Department, Washington University, St. Louis, MO1, Anatomy and Neurobiology Department, Washington University School of Medicine, St. Louis, MO2.
According to the Centers for Disease Control and Prevention, obesity is the number one health threat facing Americans today.3 While society’s transition to a higher fat diet is an obvious factor contributing to obesity, the variation that exists among individuals in response to this transition is partly genetic. Mouse models have proven to be a powerful tool for understanding complex, multi-locus diseases such as obesity. Inbred mouse strains of LG/J and SM/J (Jackson Laboratory), which were selected for large or small body size at 60 days of age, were crossed to form a population of 503 F2 mice fed on a standard diet, which allowed for analysis of the natural body and organ size variation present in this population. Quantitative trait locus (QTL) analyses using optimally spaced small nucleotide polymorphism (SNP) markers were used on liver weight data of autosomes to show regions of the genome with significant effects on liver weight, with p<.05 indicating a 95% LOD threshold. JQTL Program4 calculated LOD scores such that LOD=log10 (1/p), where p indicated the probability that no QTL is present in that region. Upon this analysis, 6 significant QTLs were found to influence liver weight. These regions produced numerous candidate genes that can be studied in future studies of gene-by-environment interaction for the complex disease of dietary obesity.