Question

In the US, consanguineous relationships bear a significant stigma. This is because the children of consanguineous matings typically have a higher than normal level of autosomal recessive diseases, including some very rare disorders. Why would this be the case if the parents are both healthy individuals?

Answer 1

Answer- consanguineous marriages result in higher chances of passing down genetic conditions especially recessive conditions ,both sex linked and autosomal Recessive , such as hemophillia and albinism respectively. This is because in a consanguineous marriage even if both Individuals appear normal , they could be carriers in case of autosomal recessive traits , which means the Genotype of both parents could be Heterozygous so the dominant allele in them supresses the effects of recessive allele and they appear normal but if they have an offspring there is a 25% chance the child will be affected and 50% chance child will be carrier. This is because both these Individuals can pass down the recessive allele to the offspring making the child affected. Both parents since related with same family origin may carry atleast one copy of recessive allele or may not carry any recessive allele ,so they appear normal.

An example-

Lets say A is for normal skin colour allele.

a= recessive allele for albinism .

So say parents are both Aa that is heterozygous .

So Aa × Aa

	A	a
A	AA	Aa
a	Aa	aa

Here aa will be genotype that results in an offspring with albinism so 25% chance . But both parents will be normal as they have one copy each of the dominant allele.

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