ESSENTIALS OF GENETICS-MODIFIED ACCESS
ESSENTIALS OF GENETICS-MODIFIED ACCESS
9th Edition
ISBN: 9780134190006
Author: KLUG
Publisher: PEARSON
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Chapter 4, Problem 1CS

CASE STUDY | But he isn't deaf

Researching their family histories, a deaf couple learns that each of them has relatives through several generations who are deaf. With a rudimentary understanding of genetics, they also learn that one of many forms of deafness can be inherited as an autosomal recessive trait. They plan to have children, and based on the above information, they are concerned that some or all of their children may be deaf. To their delight, their first child has normalhearing. The couple turns to you as a geneticist to help explain this situation.

Is it likely that these parents inherited their deafness as an autosomal recessive trait?

Expert Solution & Answer
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Summary Introduction

To analyze:

The query of a deaf couple having a normal first child that whether the deafness in the couple is due to autosomal recessive inheritance.

Introduction:

In the given case, a deaf couple learn that they had relatives who were deaf. Despite the fact and expecting some of their children to be deaf, they bear a normal firstborn baby. Deafness, also known as hearing impairment, can be caused by genetic inheritance of trait from one generation to another. Inherited deafness is present in 50% (percent) of the deaf population.

Explanation of Solution

It can be inherited in the form of autosomal recessive trait or autosomal dominant trait. In autosomal recessive deafness, both the alleles for deafness must be present in order to cause deafness; whereas in autosomal dominant deafness, single allele is able to cause deafness in the offspring.

Parents do not have both the alleles for deafness, because the first child born is normal. In case, both had a pair of recessive allele for deafness, the first child would be deaf as well. Therefore, the deafness inherited in this case is not due to autosomal recessive inheritance.

If it was a case of recessive inheritance, then

DD X DD= DD; DD; DD; DD, all the children would be deaf. But, this is not true.

D: deaf, d: normal

Conclusion

Therefore, it can be concluded that this is not the case of autosomal recessive inheritance. Parents might have inherited deafness, but not through autosomal inheritance.

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Chapter 4 Solutions

ESSENTIALS OF GENETICS-MODIFIED ACCESS

Ch. 4 - 8. The following genotypes of two independently...Ch. 4 - Given the inheritance pattern of coat color in...Ch. 4 - A husband and wife have normal vision, although...Ch. 4 - In humans, the ABO blood type is under the control...Ch. 4 - In goals, development of the beard is due to a...Ch. 4 - 13. In cats, orange coal color is determined by...Ch. 4 - In Drosophila, an X-linked recessive mutation,...Ch. 4 - Another recessive mutation in Drosophila, ebony...Ch. 4 - While vermilion is X-linked in Drosophila and...Ch. 4 - In pigs, coat color may be sandy, red, or white. A...Ch. 4 - A geneticist from an alien planet that prohibits...Ch. 4 - In another cross, the frog geneticist from Problem...Ch. 4 - In cattle, coats may be solid white, solid black,...Ch. 4 - Consider the following three pedigrees, all...Ch. 4 - Labrador retrievers may be black, brown, or golden...Ch. 4 - Three autosomal recessive mutations in Drosophila,...Ch. 4 - 24. Horses can be cremello (a light cream...Ch. 4 - Pigment in the mouse is produced only when the C...Ch. 4 - Five human matings numbered 1–5 are shown in the...Ch. 4 - Two mothers give birth to sons at the same time at...Ch. 4 - In Dexter and Kerry cattle, animals may be polled...Ch. 4 - What genetic criteria distinguish a case of...Ch. 4 - 30. The specification of the anterior-posterior...Ch. 4 - The maternal-effect mutation bicoid(bcd)is...Ch. 4 - 32. Students taking a genetics exam were...Ch. 4 - In four o'clock plants, many flower colors are...Ch. 4 - Prob. 34PDQ
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