Muscular Dystrophy Is a Group of Inherited Disorders That Lead

question 17

Multiple Choice

Muscular dystrophy is a group of inherited disorders that lead to increasing muscle cell loss and thus muscle weakness over time. There are many different types of muscular dystrophy. Symptoms can vary, although all involve muscle weakness. Duchenne muscular dystrophy (DMD) is a recessive X-linked form that leads to muscle degeneration and death usually by age 25. Symptoms begin before age 5 and include low endurance and difficulties standing. As the condition progresses, muscle tissue is replaced with adipose and other types of connective tissue. Abnormal bone development and some neurobehavioral and learning disabilities may also occur. DMD occurs as a result of a mutation in a single gene on the X chromosome. This gene codes for a particular protein, dystrophin, which plays a major role in the structure of muscle cells. The protein formed by the mutated gene is nonfunctional, and the absence of a functional protein eventually leads to cell death. A woman who is a carrier for DMD marries a man who does not have the disease. What is the probability that they will have a boy with DMD?

• A) 0 percent
• B) 25 percent
• C) 50 percent
• D) 100 percent

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Definitions:

Cardinal Positions

Refers to the primary directions in which an individual can move their eyes, aiding in the assessment of ocular muscle function.

Positive Romberg Sign

A clinical indication of a loss of proprioception, where closing the eyes increases unsteadiness or falls, used in neurological examinations.

Ortolani Sign

A clinical sign used to detect dislocation of the hip in infants, involving a specific maneuver by a healthcare provider.

Modified Allen Test

A medical test used to evaluate the blood supply to the hand, ensuring the patency of the radial and ulnar arteries.