A 5-yr old boy is diagnosed with Duchenne muscular dystrophy. There is a mutation in the promoter site for the dystrophin gene. The true statement is:
Defects that interfere with the translation reading frame or with the promoter sequence that initiates synthesis of dystrophin lead to an unstable, ineffective protein, as in Duchenne MD. Disruption of the translation process fuher down the sequence leads to production of proteins of lower molecular weight that, although present, are less active and result in the milder variety of Becker MD. Duchenne muscular dystrophy is a X-linked form of muscular dystrophies. The defect is located on the sho arm of the X chromosome. Duchenne muscular dystrophy is caused by the absence of the protein dystrophin, which is a structural protein. The large size of the dystrophin gene explains the ease at which spontaneous new mutations can occur, as in Duchenne MD. The Gower sign is a classic physical examination finding in MD and results from weakness in the child's proximal hip muscles. Ref: Lippincott's Illustrated Biochemistry, 4th Edition, Page 430
Initiation of dystrophin protein is affected
Capping of dystrophin mRNA is affected
Poly-A tail of dystrophin mRNA is affected
Termination of dystrophin protein is affected