Question

CASE STUDY #3

Read the following Case Study and then answer questions 1-2 in the space below.

AIE disease is a type of hereditary ocular disorder in which nerve tracts from the eye to the brain are damaged. Individuals diagnosed with the condition are extremely variable with respect to the symptoms they experience, causing the phenotypes to fall under a wide range of possibilities. Some examples of symptoms: mutations to the BLR gene can result in blurred vision, a faulty BLD gene leaves some individuals completely blind, and mutations to the DNC gene causes "dancing eyes" (variations in color blindness and loss of night vision). Affected individuals can even have different combinations of these symptoms. Genetic analyses have revealed over 1,000 different mutations on each of these genes, which is why symptoms are so variable. While there is no cure, doctors have noticed that a healthy diet and daily exercise can alleviate some symptoms.

QUESTIONS:

1A - 1C. Identify the three NON-Mendelian factors that influence the inheritance of AIE disease (Choose from the following: Epistasis, Incomplete Penetrance, Lethal Allele Combination, Multifactorial, Multiple Alleles, Phenocopy, Pleiotropy, Polygenic, Sex-influenced, Variable Expressivity, X Inactivation). (3 pts)

2A - 2C. Explain WHY you identified each of the factors that you did. (3 pts)

Answer 1

The Non Mendelian Factors that affect in AIE diseases are-

Pleiotrophy-The gene for sure has pleiotrophic effect because its mutation results in so many different diseased phenotypes.

Variable expressivity-The given gene has variable expressivity because in some individuals this gene mutation results in complete blindness whereas in some it only leads to the dancing eye or like inhibition of the night blindness.

Multifactorial-The disease here can be classified as multifactorial because though the disease is controlled only by one gene mutation but still a healthy and balanced lifestyle can successfully reduce its effects.So this is also a lifestyle controllef disease one the gene gets mutated so it can be termed as multifactorial.