Chapter 23, Problem 21AQP

Summary Introduction

To determine:

The characteristics of the pedigree that suggest that pancreatic cancer in the family is inherited as an autosomal dominant trait.

Introduction:

A pedigree is a pictorial representation which represents the history of a family, essentially a tree that outlines the inheritance of characteristics. When a particular disease or characteristics is observed in a person then a geneticist often studies the family history of the affected person by constructing a pedigree.

Explanation of Solution

In reference to Figure 23.1, Pancreatic cancer is inherited as an autosomal dominant trait in a family that possesses a mutated palladin gene, given in the textbook. It can be observed from the pedigree that highlighted circles are boxes with red color are cancer and the striped ones are precancerous growth.

The family tree starts with a male having cancer. This trait is then inherited by 4 out of 5 sons and none of the daughters. In third generation, it can be observed that in males either cancer is present or precancerous growths (in few females also) is present. Thus, it can be interpreted that the trait is “autosomal dominant” due to following reasons:

(1) Traits do not miss generations.

(2) Mating of affected and unaffected parents produce half of the affected children.

(3) Can be transmitted from either of a parent.

Conclusion

The characteristics of the pedigree suggest that pancreatic is inherited as an autosomal dominant trait because of the characteristics such as inheritance in most generations, affected offsprings and its transmittance from either parent.