In chick embryos, IGF2 was initially reported to be transcribed monoallelically, but some embryos
showed paternal expression and some maternal expression (Koski LB
et al, 2000).
In contrast, all subsequent publications have reported biallelic expression (O'Neil
MJ et al, 2000; Nolan
CM et al, 2001; Yokomine
T et al, 2001; Wang
G et al (2005))