Misty ( m) affects growth traits

• Published in: American journal of physiology. Regulatory, integrative and comparative physiology Vol. 275; no. 1; p. R29
• Main Authors: Truett, Gary E, Tempelman, Robert J, Walker, Jerilyn A, Wilson, J Krause
• Format: Journal Article
• Language: English
• Published: United States 01.07.1998
• Subjects: leptin receptor; obese mice; diabetes; db; obesity

The misty ( m) coat color mutation is commonly maintained in linkage disequilibrium with the obesity mutation diabetes ( Lepr ) to serve as a marker for Lepr genotype. Comparisons among Lepr genotypes are made under the untested assumption that m has no effects on traits under investigation. We tested this assumption in a population segregating m in the absence of db. Analysis of growth curves revealed that m/m mice are smaller than M/M mice by the 2nd wk of life and remain smaller through the 5th wk of life. Analysis of variance of three traits measured at 35 days of age revealed that m/m mice are 8% shorter than M/M mice, weigh 15% less, and have 21% less inguinal adipose mass. These results indicate that m affects growth traits. Therefore, when m and Lepr segregate in the same cross, interpretation of their effects is confounded by linkage. More accurate estimates of Lepr genotype effects can be made by removing m from populations segregating Lepr and using a direct assay to measure Lepr genotype.