Dhcr7 (7-dehydrocholesterol reductase) was maternally expressed in E13.5 placenta, but biallelically
expressed in E13.5 embryos (Schulz
R et al, 2006).
However, Okae H et al, (2012) concluded
that Dhcr7 by was not imprinted in mouse placenta or trophoblast stem cells. They reported
relatively high expression in maternal material suggesting that the apparent imprinted maternal
expression of Dhcr7 was attributable to maternal contamination of placental tissues. This result is
concordant with the caution
from Proudhon and Bourc'his (2010) that maternal contamination of placental tissues may
cause apparent imprinted maternal expression.