Genetic modification is a rapidly developing field of medicine used to address hereditary disorders. Depending on the target cell type, therapeutic genetic modification is classified as either somatic or germ-line.
Identify which classification of gene therapy (somatic or germ-line) results in genetic alterations that can be inherited by the patient's offspring, and explain why.
Compare somatic and germ-line gene therapy with respect to:
When integrating a transgene into a host genome using viral vectors, insertion of the foreign DNA sequence can disrupt the expression of existing, non-targeted genes on that same chromosome.
Explain how the integration of an exogenous gene sequence can alter the expression or functioning of adjacent host genes.
Severe Combined Immunodeficiency (SCID) caused by adenosine deaminase (ADA) deficiency is a recessive disorder. It can be treated by introducing a functional, normal copy of the ADA gene into the patient's hematopoietic stem cells.
In contrast, Spinocerebellar Ataxia Type 1 (SCA1) is a progressive neurodegenerative disorder caused by a dominant mutation in the ATXN1 gene. This mutation produces a toxic, misfolded form of the ataxin-1 protein that aggregates in cerebellar neurons.
Suggest why standard gene addition therapy (introducing a normal, functional copy of the ATXN1 gene) would not be an effective treatment for SCA1.