1.4.18 Describe the principles of gene therapy and distinguish between somatic and germ line therapy.

- Gene therapy is the insertion of a normal allele of a gene into cells to replace a faulty allele that causes an inherited disorder. 

- This could be done in the very early embryo (germ line therapy) or in the affected body part or parts (somatic therapy).

Somatic Therapy

Identify the gene involved, make copies of the normal allele and insert into a vector ( e.g. viruses/ liposomes), use the vector to insert the allele into the target cells. 

Germ Line Therapy

- Involves altering the germ cells - the reproductive cells - of the body of very early embryos immediately after in vitro fertilisation, so that the faulty genes are no longer passed on.

Differences

Germ line affects gametes; somatic affects body cells; germ line can be passed onto the next generation; somatic gene therapy cannot be passed onto the next generation.