Which of the following statements is true regarding genomic imprinting?

A. It may explain the transmission of Duchenne muscular dystrophy.


B. It explains cases where the gender of the parent from whom an allele is inherited affects the expression of that allele.


C. It is found in X inactivation in human females during early embryonic development.


D. It explains sex-linked inheritance in which the sex of the parent carrying the mutant allele determines whether male or female offspring will be affected.


E. It is greatest in females because of the larger maternal contribution of cytoplasm.

Which of the following statements is true regarding genomic imprinting?
Perhaps the most widely accepted explanation for the occurrence of genomic imprinting is the “parental conflict hypothesis” (Moore and Haig 1991). The hypothesis states that the inequality between parental genomes due to imprinting is a result of the differing interests of each parent. The father is more interested in the growth of his offspring, at the expense of the mother. The mother's interest is to conserve resources for her own survival while providing sufficient nourishment to current and subsequent litters. Accordingly, paternally expressed genes tend to be growth promoting whereas maternally expressed genes tend to be growth limiting (Moore and Haig 1991).


Another hypothesis behind the origins of genomic imprinting is that this phenomenon evolved to silence foreign DNA elements, such as genes of viral origin. There appears to be an over-representation of retrotransposed genes, that is to say genes that are inserted into the genome by viruses, among imprinted genes. It has also been postulated that if the retrotransposed gene is inserted close to another imprinted gene, it may just acquire this imprint
Reply:e

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