A research team is developing gene therapy protocols to treat Adenosine Deaminase deficiency (ADA-SCID), an autosomal recessive disorder. They are comparing a somatic gene therapy protocol (using a retroviral vector to modify hematopoietic stem cells ex vivo) with a proposed germ-line gene therapy protocol using CRISPR-Cas9 on a single-celled zygote.
Which of the following statements correctly compares the biological consequences of these two approaches?
Somatic gene therapy of hematopoietic stem cells prevents the mutated allele from being passed on to the patient's biological children, as the stem cells are fully corrected.
Germ-line gene therapy involves modifying cells of the adult reproductive organs, meaning the therapeutic effects are limited only to the treated individual's somatic tissues.
Somatic gene therapy permanently alters the genome of all cells in the patient's body, whereas germ-line therapy only transiently expresses the therapeutic protein in gametes.
Somatic gene therapy results in the therapeutic gene being present only in specific targeted body cells, whereas successful germ-line gene therapy results in the gene being present in all cells of the developed offspring.
14 exam-style questions on OCR A A Level Biology Manipulating genomes. Each one has a worked solution and a mark scheme showing where the marks go.