Mutation of the peripheral myelin protein 22 (PMP22) gene, which causes demyelination of peripheral neurons, is a more common cause of Charcot-Marie-Tooth disease. In which cells is the PMP22 gene important for normal function?

Question

  Charcot-Marie-Tooth is the most commonly inherited peripheral neuropathy, and has no known cure. Patients suffer damage to motor and sensory neurons, leading to degeneration of muscles and gradual loss of motor control.

A.  Schwann cells
B.  preganglionic neurons
C.  postganglionic neurons
D.  oligodendrocytes
E.  interneurons

Clarify Question
· What is the key concept addressed by the question?
What type of thinking is required

Gather Content/Choose Answer
· What do you already know about components of the nervous system? What other information is related to the question?

Reflect on Process
· Did your problem-solving process lead you to the correct answer? If not, where did the process break down or lead you astray? How can you revise your approach to produce a more desirable result?

Answer 1

A.  Schwann cells


Clarify Question
· What is the key concept addressed by the question?
        o The question is asking you about the causes of demyelination in peripheral neurons. · What type of thinking is required?         o This question is asking you to apply your knowledge about the cells in the PNS and how they could affect demyelination of axons.

Gather Content/Choose Answer
· What do you already know about components of the nervous system? What other information is related to the question?
        o To solve this problem, you’ll need determine which cells affect myelination of axons, which are Schwann cells and oligodendrocytes. Knowing this, you then need to apply your knowledge of the difference between oligodendrocytes and Schwann cells and their functions. Oligodendrocytes are cells that myelinate axons in the central nervous system while Schwann cells serve the same purpose in the peripheral nervous system. Therefore, the function of Schwann cells is affected by the PMP22 gene.

Reflect on Process
· Did your problem-solving process lead you to the correct answer? If not, where did the process break down or lead you astray? How can you revise your approach to produce a more desirable result?
        o If you figured out the correct answer, good job! If not, where did you go wrong? Did you remember that oligodendrocytes are found in the central nervous system and not the peripheral nervous system? Did you remember that Schwann cells are responsible for myelination of peripheral nerves and that myelination increases the conduction of action potentials?