LAMA2-congenital muscular dystrophy (LAMA2-CMD) is caused by mutations in the LAMA2 gene, encoding the ?2 chain of laminins 211/221, components of the extracellular matrix. Using the dyW mouse model for LAMA2-CMD, we have previously shown that LAMA2-CMD starts in utero between embryonic day 17.5 and 18.5 with a reduction in the pool of muscle stem cells (MuSCs)/myoblasts and impaired muscle growth. To determine the cellular and molecular mechanisms involved in this fetal muscle phenotype in the dyW model we asked whether dyW muscles displayed alterations in pathways regulating cell proliferation and survival. Moreover, we generated a Lama2-deficient C2C12 myoblast cell line to use as a parallel model. Skeletal muscles from dyW-/- fetuses and Lama2-deficient C2C12 cells both showed changes in the expression of genes linked to cell cycle regulation and cell survival. Furthermore, we found that Lama2-deficient C2C12 cells exhibit a decreased proliferation rate in vitro, possibly explained by cell cycle arrest at G1/G0 phase. Both models also showed increased expression of oxidative stress markers, raising the possibility that oxidative stress, which is known to influence cell cycle progression, may be involved. DNA damage can be a major consequence of oxidative stress in cells, and Lama2-deficient C2C12 cells show increased levels of DNA damage markers. In conclusion, our study implicates cell cycle deregulation, oxidative stress and DNA damage as players in the onset of LAMA2-CMD. Further studies will address whether and how deregulation of these cellular processes leads to the reduction in the number of MuSCs/myoblasts and impaired muscle growth observed in E18.5 dyW muscles. These results are particularly important since they contribute for a better understanding of the first stages of LAMA2-CMD onset, which is essential to design therapies that specifically target the primary events underlying this incurable, and often lethal, disease.