Question

How does maternal inheritance differ from X-linked inheritance? How can you distinguish both in pedigrees and experimentally?

Answer 1

In maternal inheritance, the owner of the genes is always mother. It is caused because of the transmission of organelle genome from the mother to the offspring. It is never transmitted from father to the offspring. The reason of this type of inheritance is that the egg of the mother contains maximum amount of cytoplasm and therefore organelles and so the donor of Mitochondria and chloroplast to the progeny is the mother and not the father.

In case of X linked inheritance, the transmission can be both from mother and father because it is related to the genes located on chromosome. And X chromosome in sons from the mother and in daughters come from both father and mother.

In a Pedigree, maternal inheritance will always show transmission of trait from the mother to all the progeny. But in sex linked inheritance, the Pedigree will show the transmission of trait from both mother and father.

Experimentally we can determine whether a trait is maternal inheritance or sex linked, by PCR. We will use specific primers.

In case of maternal inheritance, the mother and all her progenies will show the formation of a PCR product but the father will not show. The template DNA will be the one isolated from mitochondria in case of human beings because we do not have chloroplast.

In case of sex linked inheritance, if the daughter is affected, there are equal chances that the mother and father and affected progeny will show the PCR product.

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