How does genomic imprinting relate to the concept of epigenetics?
1 Answer
Genomic imprinting is an epigenetic phenomenon that causes genes to be expressed in a manner specific to their parent of origin.
Explanation:
Genomic imprinting is an inheritance out of Mendelian borders. Many of inherited diseases and human development violates Mendelian Laws of inheritance. This way of inheriting is studied in epigenetics. Epigenetics shows that gene expression undergoes changes more complex than modifications in the DNA sequence. It includes the environmental influence on the gametes before conception.
Genetic imprinting is a process of silencing genes through DNA methylation. The repressed allele is methylated, while the active allele remains unmethylated. Genomic imprinting occurs when two alleles at a locus are not functionally equivalent and is considered the primary epigenetic phenomenon that can lead to the manifestation of parent-of-origin effect. Epigenetic changes can be induced by environmental factors at different times in life.
When epigenetic changes occur in sperm or egg cells that lead to fertilization, epigenetic changes are inherited by the offspring.
Imprinting is a dynamic process. It must be possible to erase and re establish imprints through each generation so that genes are imprinted in an adult may still be expressed in that adult's offspring. The nature of imprinting must therefore be epigenetic rather than DNA sequence dependent. Genomic imprinting uses the cell's normal epigenetic machinery to regulate parental specific expression.
It is now known that there are atleast 80 imprinted genes in human and mice, many of which are involved in embryonic and placental growth and development. Forms of genetic imprinting have been demonstrated in fungi, plants and animals.
