MGI:2387629Homozygous deficient mice display embryonic lethality before somite formation with impaired inner cell mass proliferation. Substitutions in RRM2 or low-complexity (LCD) domains affect mRNA splicing. Homozygosity for these mutations is embryonic lethal on B6 strain backgrounds. The LCD mutation leads to an adult-onset neuromuscular phenotype accompanied by motor neuron loss and neurodegenerative changes on B6-D2 background. Heterozygosity for p.N267S mutation affects neural stem cells and leads to neurological defects.