Gene therapy attempts to treat an inherited disease by

Explanation

A working allele is delivered, usually inside a modified virus or a liposome, so that the patient's own cells can make the missing protein, and cystic fibrosis and severe combined immunodeficiency are the standard examples. Somatic gene therapy treats the patient only, while germ line therapy would alter every descendant and is banned in most countries. Current difficulties are keeping the gene expressed and avoiding an immune reaction to the vector.