Dystrophin Gene and Muscular Dystrophy

The video explains how the absence of the dystrophin protein leads to Duchenne muscular dystrophy (DMD). Dystrophin links muscle fibers to the sarcolemma, acting as a shock absorber. Without it, muscle fibers are damaged, leading to DMD. The dystrophin gene, the largest in the human genome, consists of 79 exons. Mutations often involve exon deletions, affecting the reading frame. Frameshift mutations result in DMD, while in-frame mutations may cause Becker muscular dystrophy. Exceptions exist, and muscle biopsies can help diagnose the condition.

What is the primary function of the dystrophin protein in muscle fibers?

• To store calcium ions

• To transport oxygen in the bloodstream

• To link actin to a protein complex in the sarcolemma

• To provide energy to muscle cells

What happens to muscle fibers in the absence of dystrophin?

• They produce more creatine kinase

• They regenerate more quickly

• They leak intracellular components and become damaged

• They become stronger and more flexible

How many exons does the dystrophin gene consist of?

• 50

• 100

• 150

• 79

What is the result of a frameshift mutation in the dystrophin gene?

• Increased production of dystrophin

• No effect on the protein

• Production of a fully functional dystrophin protein

• Production of a truncated, unstable dystrophin protein

What is the reading frame rule in the context of the dystrophin gene?

• It defines the sequence of amino acids in a protein

• It describes how exons connect to each other during transcription

• It determines the number of exons in a gene

• It explains how proteins are transported in muscle cells

What type of mutation allows for the production of partially functional dystrophin?

• Point mutation

• Silent mutation

• In-frame mutation

• Frameshift mutation

What is a possible outcome for patients with in-frame mutations?

• They may develop Becker Muscular Dystrophy

• They never show symptoms of muscular dystrophy

• They always develop Duchenne Muscular Dystrophy

• They have increased muscle strength

What percentage of cases does the reading frame rule apply to?

• 100%

• 50%

• 70%

• 90%

What is the main difference between Duchenne and Becker Muscular Dystrophy?

• Duchenne is caused by in-frame mutations, Becker by frameshift mutations

• Becker affects only adults, Duchenne affects only children

• Duchenne is more severe than Becker

• Becker is caused by a different gene than Duchenne

Why might a muscle biopsy be necessary in some cases of muscular dystrophy?

• To determine the patient's age

• To assess the patient's diet

• To quantify the amount of dystrophin

• To measure the amount of creatine kinase