Lmod3-KO mice were born at Mendelian ratios from heterozygous intercrosses and were indistinguishable from their WT littermates at birth. However, Lmod3-KO mice gradually displayed a failure-to-thrive phenotype, with the size difference between the KO mice and their WT littermates becoming more pronounced with age. In order to ascertain that the failure to thrive was not due to difficulty in suckling or breathing, the authors confirmed that KO mice had milk spots comparable to those of their WT littermates. Furthermore,
conventional histologic analysis showed that the diaphragms were unaffected. The KO mice survived to adulthood, had the same lifespan as that of their WT littermates, and could breed successfully. However, they remained runted compared with their WT littermates. The degree of runting varied between mice, likely due to the mixed background, and there were cases of extreme failure to thrive. Both male and female mice displayed the same growth curves.
The hearts of KO mice were also smaller starting from P7 and throughout adulthood. Despite the smaller-sized hearts, cardiac function was minimally impaired in the KO animals suggesting that loss of LMOD3 in skeletal muscle was primarily responsible for the failure-to-thrive phenotype.
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