- Duchenne muscular dystrophy (DMD) is a sex‑linked genetic disorder caused by a recessive allele resulting from mutations in the X‑linked dystrophin gene. This causes the degeneration of cardiac and skeletal muscle. These mutations can include deletions, insertions and base substitution mutations.
(a) Using a Punnett grid, deduce the probability of inheriting DMD if an unaffected male has offspring with a female carrier. [3]
(b) Distinguish between deletion and insertion mutations. [1]
diagram of gene‑editing process correcting dystrophin expression from white‑blood cells to pluripotent stem cells to cardiac cells
(c) Explain ways in which CRISPR‑Cas9 gene editing could be used to change the mutated dystrophin protein produced. [3]
(d) Suggest one reason for the use of pluripotent instead of multipotent stem cells in this process. [1]