Interspecific recombinant congenic strains between C57BL/6 and mice of the Mus spretus species : a powerful tool to dissect genetic control of complex traits

Complex traits are under the genetic control of multiple genes, often with weak effects and strong epistatic interactions. We developed two new collections of mouse strains to improve genetic dissection of complex traits. They are derived from several backcrosses of the Mus spretus SEG/Pas or STF/Pas strains on the C57BL/6J background. Each of the 55 Interspecific Recombinant Congenic Strains (IRCS) carries up to seven SEG/Pas chromosomal segments with an average size of 13.4 Mb, totalizing 1.26% of the genome. The complete series covers 38% of the SEG/Pas genome. As a complementary resource, six partial or complete interspecific consomic strains were developed, and increase genome coverage to 43.3%. To evaluate the usefulness of these strains for the QTL mapping, 16 IRCS were compared with C57BL/6J for seven hematological parameters. Strain 66H, which carries three SEG/Pas chromosomal segments, had lower red blood cell volume and higher platelet count than C57BL/6J. Each chromosomal segment was isolated in a congenic strain to evaluate individual effects. Congenic strains were combined to assess epistasis. Our data show that both traits were controlled by several genes with complex epistatic interactions. IRCS are therefore useful to unravel QTLs with small effects, and gene by gene interactions.

Key Words: Complex traits, Interspecific Recombinant Congenic Strains, Mouse, Mus spretus, QTL

Online ISS 1091-6490
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