Summary
Imprinted genes regulate placental growth, balancing parental interests in resource allocation.
In depth
The parental conflict hypothesis (Haig) says paternal genes favour growth (IGF2) while maternal genes restrain it (H19, IGF2R). Disruption causes disorders such as Beckwith-Wiedemann (overgrowth) and Silver-Russell syndromes (undergrowth).
Imprinted genes balance resource demands between mother and fetus. Imprinting errors may occur in assisted reproduction.
Example: paternal IGF2 promotes fetal growth.
Imprinted genes are expressed from only one parental allele, depending on epigenetic marks (DNA methylation) set in the germline. About 100 to 200 are known in mammals, many acting in the placenta and fetus.
Haig's conflict hypothesis suggests paternally expressed genes, such as IGF2, push for more resources from the mother for the fetus, while maternally expressed genes, such as H19 and IGF2R, restrain growth, balancing the mother's interest in future offspring. Imbalance causes disorders: loss of paternal 15q11-13 gives Prader-Willi syndrome, loss of maternal gives Angelman syndrome, and IGF2 overexpression causes Beckwith-Wiedemann overgrowth. Imprinting also explains why mammals cannot reproduce by parthenogenesis.
Example: in mice, androgenetic embryos have poor embryos but large placentas.
Key idea: parents have conflicting evolutionary interests.
Frequently asked questions
What is Genomic Imprinting in Placenta?
Imprinted genes regulate placental growth, balancing parental interests in resource allocation.
Which area of biology covers Genomic Imprinting in Placenta, and how advanced is it?
Genomic Imprinting in Placenta is one of the 54 topics in Reproduction & Endocrinology. It is rated Advanced, so it suits learners who want specialist depth. Related topics in this area include Evolution of Placentation, Parthenogenesis, Pregnancy.
Can you give an example of Genomic Imprinting in Placenta?
Uniparental embryos form abnormal placentas.
What should I learn before Genomic Imprinting in Placenta?
Work through the Beginner topics in Reproduction & Endocrinology first, such as Reproduction, Asexual Reproduction, Sexual Reproduction, then return to Genomic Imprinting in Placenta. Advanced topics assume the Intermediate vocabulary.
What topics are related to Genomic Imprinting in Placenta?
The closest topics to Genomic Imprinting in Placenta are Evolution of Placentation, Parthenogenesis, Pregnancy, Oogenesis. Comparing them side by side is a good way to see how the ideas connect.
How can I check that I understand Genomic Imprinting in Placenta?
Read the summary and the in-depth section, then use the quick check on the interactive lesson for Genomic Imprinting in Placenta. To practise the whole of Reproduction & Endocrinology, use the Reproduction & Endocrinology quiz.
How is Genomic Imprinting in Placenta different from Evolution of Placentation?
Genomic Imprinting in Placenta: Imprinted genes regulate placental growth, balancing parental interests in resource allocation. Evolution of Placentation: Viviparity and the placenta evolved independently many times across vertebrates. Read both side by side and note what each one explains.
How should I study Genomic Imprinting in Placenta step by step?
First, read the summary and write the definition in your own words. Second, read the in-depth section and note any example. Third, compare it with Evolution of Placentation and explain the difference aloud. Finally, take the Reproduction & Endocrinology quiz and come back to this page for any question you miss.