esearching their family histories, a deaf couple learns 1.Is it likely that thes
ID: 69001 • Letter: E
Question
esearching their family histories, a deaf couple learns 1.Is it likely that these parents inherited their deafness as an that each of them has relatives through several genera autosomal recessive trait? tions who are deaf. With a rudimentary understanding 2.What is the likelihood that each future child will be deaf? of genetics, they also learn that one of many forms of deafness2. What is the likelihood that eac recessi sions could be drawni have children, and based on the above information, they are been deaf? concerned that some or all of their children may be deaf. To their delight, their first child has normal hearing. The couple turns to you as a geneticist to help explain this situation.Explanation / Answer
Autosomal recessive is one of several ways that a disorder can be passed through families.In autosomal recessive disorder two copies of an abnormal gene is present due to mutation in the twenty second non-sex chromosome.Recessive inheritance means both genes in a pair must be abnormal to cause disease.
People with only one defective gene in the pair are called carriers and these poeple donot affect to the disease.
But, in autosomal dominant inheritance genetic deafness is caused by mutation in one copy of an autosomal gene and the other normal gene cannot compensate for the effects of the change.In this autosomal dominant inheritance eventhough one mutant gene is seen in genetic pair it exhibits disorder.
In the situation given in the above question both the parents are deaf but their first born child is normal because they have only one abnormal gene in autosomal gene pair.
1)In autosomal recessive trait both the genes in gene pair are mutated to cause disorder.So,if these parents are autosomal recessive traits then they would inherited their deafness to their children.
2)There is a chance that such a couple will have an affected child is one in four for every pregnancy that is 25%.
3)If their first child had been deaf then there is a possibility that the remaining child would also be deaf because their parents are deaf due to autosomal recessive inheritance and it is likely that these are inherited their deafness.
But in the question given the deaf parents given birth to normal child.If these parents exhibit autosomal recessive syndrome then their child should be deaf but here the child is normal even though the parents are deaf so,in this case the parents exhibit autosomal dominant inheritance.
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