Table 1.

Glossary of terms

AAV (adeno-associated virus)	A viral vector system used for gene delivery.
Chimera	A single organism composed of cells from different zygotes.
Germ line therapy	Insertion of DNA into germ line cells (egg or sperm) so that the offspring will have the inserted gene.
gRNA	Guide RNA.
Hematopoietic stem cells	Unspecialized precursor cells that will develop into mature blood cells.
Pluripotent stem cells	Stem cells that can become all cell types found in an implanted embryo, fetus, or developed organism (excluding trophoblast and placenta).
Recombinant DNA	A novel DNA sequence formed by the joining, usually in vitro, of two non-homologous DNA molecules.
Retroviral vector	A disabled RNA virus in which the viral genes have been replaced with engineered sequences.
RuvC	An endonuclease domain named for an E. coli protein involved in DNA repair.
sgRNA	Single guide RNA.
Stem cells	Cells with the ability to divide for indefinite periods in culture and to give rise to specialized cells.
tracrRNA, trRNA	Trans-activating crRNA.