The ICR for this cluster is in intron 2 of Igf2r, it is methylated on the maternal allele and
contains the Airn promoter (Sleutels
F et al, 2002). The mechanism through which the Airn transcript or the act of transcribing Airn
imprints adjacent genes (Igf2r, Slc22a2, Slc22a3) is unclear (Seidl
C et al, 2006).
Okae H et al (2012) confirmed
imprinted maternal expression of this gene in the placenta.