What is the significance of a shift to the left in the threshold value of liability in a threshold of liability model for the expression of a complex health problemwith genetic influences?
A)The threshold required for disease expression increases as the population ages.
B)The number of affected individuals within the population has decreased.
C)The population examined for the potential problem is getting larger.
D)The threshold required for disease expression is lower.

Question

Quizplus · Accepted Answer

A model of the liability threshold for a complex trait indicates how high the risk is in the general population and at what point risk is high enough so that having the disease or trait is likely. The top of the bell curve represents the mean of the population, or the liability (risk) of most of the population. The dotted line represents the average number of risk alleles carried by most of the population. For every trait there is a theoretical threshold, which indicates the point at which the number of risk alleles needed to express the disorder has just been met. All points to the right of the threshold line are designated as "affected." As the line shifts to the left, more people within the study population meet the minimum threshold for expression of the complex problem.

What Is the Significance of a Shift to the Left