Question

A 14-year-old boy presents to his family physician with complaints of muscle weakness that has been affecting his ability to play soccer. Physical examination reveals gross enlargement of his calf muscles, and a biopsy reveals active fiber degeneration and regeneration with significant replacement by fat and connective tissue. The boy's family history is positive for similar symptoms in a maternal uncle, whose condition progressed to a wheelchair-bound state by the age of 35 years. Which of the following is the mode of genetic inheritance of this disorder?

A. Autosomal dominant
B. Autosomal recessive
C. Mitochondrial inheritance
D. Somatic mutation
E. X-linked dominant
F. X-linked recessive

Answer 1

The mode of genetic inheritance for the described disorder is X-linked recessive, specifically Duchenne muscular dystrophy.

Step-by-step explanation:

The mode of genetic inheritance for the disorder described in the case is X-linked recessive. The symptoms in the patient, such as muscle weakness, calf muscle enlargement, and a positive family history, are consistent with Duchenne muscular dystrophy (DMD), which is an X-linked recessive disorder. DMD primarily affects males and is caused by a mutation in a recessive gene on the X chromosome.