Difference between Somatic and Germline gene therapy

Genes are introduced into somatic cells, it is called somatic cell gene therapy. If genes are introduced into eggs or zygotes, it is called germline gene therapy.

Somatic Therapy for SCID

Difference between 

Somatic and Germline gene therapy

	Somatic therapy	Germline therapy
1	Healthy genes introduced into the somatic cells	Healthy genes introduced into the germ cells (sperm, egg, zygotes etc).
2	Changes are not heritable and is confined to the individual.	Changes are heritable and will pass on to the future generations.
3	Techniques for somatic cell culture, introduction of healthy gene, and re implantation back to body. All these steps are successfully developed.	Many practical difficulties in introducing healthy genes to germ cells.
4	Not much ethical issues attached	Many ethical problems yet to be answered.
5	Most often it may not be possible to achieve normal level of expression similar to that of normal gene.	High frequency of insertional mutations are observed often lead to teratogenic* consequences.

* Teratogenic: causing malformation of embryo or foetus