Chapter 11, Problem 1NS.1QC

How may a pedigree pattern be used to determine if a disease is autosomal dominant or autosomal recessive?

Summary Introduction

To determine:

How pedigree pattern can be used to determine whether a disease is autosomal dominant or autosomal recessive.

Introduction:

Pedigree determines the biological relationship between an individual with their family or ancestors by using the standard symbols. The pedigree is important to predict as it helps in determining the dominant or recessive inheritance pattern of the traits and the genetic disorders related to it.

Explanation of Solution

Pedigree analysis theoretically determine about the transmission pattern of a genetic disease from one generation to the other. A disorder could be in autosomal dominant, autosomal recessive and X linked dominant or recessive conditions.

The characteristics of autosomal dominant traits are:

• The one affected parent can produce affected progeny. In autosomal dominant inheritance, the trait will occur in every generation.

• The affected number of male and females are roughly equal.

• In autosomal dominant the expression of a trait does not depend on the gender of an individual.

• Each affected parent may not produce affected offspring as they could be carrier of the dominant disorder.

• The probability of inheriting the disease by each offspring from both affected parents is 0.5.

The characteristics of autosomal recessive traits are:

• In autosomal recessive, the trait will not occur in every generation.

• The affected number of male and female are not equal.

• Both normal parents could produce affected offspring as they could be carrier of the affected allele.

• The probability of inheritance of disease by one out of every four offspring is 0.25.

With the help of above characteristic, it is easy to use pedigree analysis used to determine whether a disease is autosomal dominant or autosomal recessive.

Conclusion

Depending upon the characteristics of dominant and recessive disorders, the transmission of a disorder could be predicted through pedigree.