In mice a type of epigenetic change that is inherited in gametes from either the

Question

In mice a type of epigenetic change that is inherited in gametes from either the female or male parent represses the gene from either the maternal or paternal side. Name this type of epigenetic change: If a male mouse is heterozygous for a mutation in the lgf2 gene, which controls offspring size, and a female is homozygous for non-mutant version, what phenotypes (size of offspring) would be expected from a cross, if this gene is repressed in female gametes? Describe what epigenetic changes to DNA are and give example (s) of why they might occur:

Explanation / Answer

a). This epigenetic change is known as "genomic imprinting."

The genomic imprinting refers to the epigenetic modifications to the DNA in which either the maternal or paternal copy of a specific gene is silenced. Means, the chances of expression of a trait depends upon from which parent we are inheriting the allele. The resulting phenotypes of the disease can be varied in severity, onset age and symptoms.

b). The inheritance of Igf2 gene shows genomic imprinting, means the allele inherited from one parent is active and the other allele inherited from the other parent remains inactive. In case of Igf2, only the allele inherited from the father is active.

Mother Igf2 Igf2 X father Igf2 Igf2m = Igf2 Igf2 (1/2 normal, one allele from the father and another from the mother), Igf2 Ifg2m (dwarf, Igf2 mutant from father).

c).

The heritable changes in gene expression which are not due to underlying DNA sequence change are said to be “epigenetic changes.” Methylation of DNA suppresses gene expression, and the change in this DNA expression, which is acquired during a person’s life time, can be passed to their offspring.

Thus, the environmental exposure of a person, during his lifetime, such as famine, abundance of food and a person’s habits such as alcoholism and cigarette smoking, bring changes to their gene expression and this change is passed to their offspring and thus, can affect their future generations. Thus, the grand children experience their grandparent’s health which is a so called “transgenerational response.”

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