Journal of Heredity Advance Access published online on June 9, 2008
Journal of Heredity, doi:10.1093/jhered/esn040
Brief Communication |
Fine Mapping of "Mini-Muscle," a Recessive Mutation Causing Reduced Hindlimb Muscle Mass in Mice
From the Department of Nutrition, University of North Carolina, Chapel Hill, NC 27599 (Hartmann, Muñoz, and Pomp); the Department of Biology, University of California, Riverside, CA 92521 (Garland, Hannon, and Kelly); the Department of Cell and Molecular Physiology, Carolina Center for Genome Sciences, University of North Carolina, Chapel Hill, NC 27599 (Pomp)
Address correspondence to D. Pomp at the address above, or e-mail: dpomp{at}unc.edu.
Prolonged selective breeding of Hsd:ICR mice for high levels of voluntary wheel running has favored an unusual phenotype (mini-muscle [MM]), apparently caused by a single Mendelian recessive allele, in which hindlimb muscle mass is reduced by almost 50%. We recently described the creation and phenotypic characterization of a population suitable for mapping the genomic location of the MM gene. Specifically, we crossed females from a high-runner line fixed for the MM allele with male C57BL/6J. F1 males were then backcrossed to the MM parent females. Backcross (BC) mice exhibited a 50:50 ratio of normal to MM phenotypes. Here, we report on linkage mapping of MM in this BC population to a 2.6335-Mb interval on MMU11. This region harbors 
100 expressed or predicted genes, many of which have known roles in muscle development and/or function. Identification of the genetic variation that underlies MM could potentially be very important in understanding both normal muscle function and disregulation of muscle physiology leading to disease.
Corresponding Editor: Susan J. Lamont
Received March 7, 2008
Revised March 7, 2008
Accepted April 17, 2008