Question

Mutations occur when DNA is not properly copied. There are multiple types of mutations that cause changes to DNA sequences. Most mutations go unnoticed and undetected. However, when a change in DNA affects the resulting amino acid, a change in phenotype can occur. Two main categories of mutations that can cause phenotypic variation are germ-line mutations and somatic mutations. The diagram illustrates the differences between the two types of mutations. Poliosis is characterized by sections of hair growing without pigment. An individual with poliosis is shown.

Poliosis can be caused by a germ-line mutation or a somatic mutation. What evidence would best support that the individual's poliosis is caused by a germ-line mutation?
 
 
A. The affected individual was born with poliosis. 
 
B. The affected individual developed poliosis later in life. 
 
C. The affected individual has a family history of poliosis. 
 
D. The affected individual had no family history of poliosis.

Answer 1

C

A germ-line mutation is present in the gametes and can be inherited, so finding multiple affected family members (a family history of poliosis) is the strongest evidence that the mutation is germ-line rather than a somatic change occurring only in that individual.