Ido1 (indoleamine 2,3-dioxygenase 1) showed imprinted maternal expression of both transcripts in
mouse placentas (Spinelli P et al, 2019).
The Ido1 promoter showed methylation in sperm and unmethylation in oocytes.
The neighbouring Ido2 gene was also imprinted.
Studies using Ido1 deficient mice showed that Ido1 alleles of paternal origin were functionally
inactivated, consistent with genomic imprinting (Baban B et al, 2004).