Use of pre t alpha or functional variant thereof for expanding tcr alpha deficient t cells

A method for genetic modification of a cell comprising:

• providing human primary T cells comprising a target DNA gene sequence;
• culturing the T cells;
• electroporating mRNAs encoding two half-TALE-nucleases that together target said target DNA gene sequence into the T cells;
• wherein one of said mRNAs encodes a half-TALE-nuclease targeting said target DNA gene sequence,
• wherein another of said mRNAs encodes the other half-TALE-nuclease targeting said target DNA gene sequence;
• and
• introducing into the T cells an exogeneous nucleic acid comprising at least a sequence homologous to a portion of the target nucleic acid sequence;
• and
• transiently expressing the half-TALE-nucleases in the cells to generate a double-strand break at the DNA target gene sequence such that homologous recombination occurs between the target nucleic acid sequence and the exogeneous nucleic acid to generate a sufficient number of T cells comprising the exogeneous nucleic acid integrated into the target gene for immunotherapy.