RTL1 (retrotransposon-like 1, Mar1, MART1, PEG11) showed allelic expression
bias in fibroblast cell lines. Exclusive paternal expression was then shown in four informative
parent-offspring trios (Morcos L et al (2011).
Quantitative real-time PCR showed that RTL1 expression level was about five times higher in the
placental samples of two patients with paternal uniparental disomy 14 compared to controls,
consistent with paternal expression (Kagami M et al, 2012).
Baran Y et al (2015) reported that allelic expression
of RTL in adrenal gland, brain and pituitary tissue was consistent with imprinting (using RNA-seq).