Genomic imprinting is a method of gene regulation whereby a gene is express
ed in a parent-of-origin-dependent fashion; however, it is hypothesized tha
t imprinting should not occur in oviparous taxa such as birds. Therefore, w
e examined the allelic expression of two genes in the chicken that are reci
procally imprinted in most mammals, mannose 6-phosphate/insulin-like growth
fnctor 2 receptor (M6P/IGF2R) and insulin-like growth fnctor 2 (IGF2). Sin
gle nucleotide polymorphisms were identified in these genes, and cDNA was p
repared from several tissues of embryos heterozygous for these polymorphism
s. Both alleles of M6P/IGF2R and IGF2 were expressed in all tissues examine
d by RT-PCR. Since the expression of these genes was independent of the par
ent from which they were inherited, we conclude that neither M6P/IGF2R nor
IGF2 are imprinted in the chicken.