A 15-Year-Old Boy Is Evaluated for Progressive Lower Extremity Weakness

question 286

Multiple Choice

A 15-year-old boy is evaluated for progressive lower extremity weakness.  The patient has had difficulty running and keeping up with peers for the past several years and has sprained his ankles on multiple occasions.  His father also experienced similar symptoms beginning at the same age and became wheelchair bound.  Physical examination shows weakness and atrophy of the distal lower extremity muscles.  There is bilateral pes cavus deformity.  Ankle reflexes are absent, and sensation to vibration is also absent in the feet.  Abnormal function of which of the following is the most likely cause of this patient's condition?

• A)Muscle dystrophin
• B)Myelin protein
• C)Ryanodine receptors
• D)Synaptic vesicles
• E)Tau protein

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Definitions:

Third Market

A trading segment where exchange-listed securities are traded over-the-counter (OTC) between institutional investors, typically by brokerage firms or securities dealers to provide liquidity.

Fourth Market

A market where institutional investors trade securities directly among themselves without the use of a broker.

Difference

The result obtained when one quantity is subtracted from another.

Common Stock

A type of equity ownership in corporations, where shareholders have voting rights and potentially dividends.