A 4 year old boy is brought to clinic because of frequent falls and difficulty climbing stairs. Examination shows proximal lower extremity weakness, enlarged calves, and use of his hands to rise from the floor. Serum creatine kinase is markedly elevated. Which of the following is the most likely underlying defect?
- A)Postsynaptic acetylcholine receptor antibodies
- B)Expansion of CTG repeats in the DMPK gene
- C)Mutation in the chloride channel of skeletal muscle
- D)Deletion causing frameshift mutation in the dystrophin geneGABARITO
- E)Mutation in the ryanodine receptor causing malignant hyperthermia
Explicação
Deletion causing frameshift mutation in the dystrophin gene is correct. Duchenne muscular dystrophy is an X linked recessive disorder caused by absent dystrophin due to out of frame mutation, leading to progressive myofiber degeneration. Gowers maneuver, calf ... Ver explicação completa e trilha adaptativa →