TIMELINE-Gene therapy's long road to market

LONDON, Aug 8 (Reuters) - Gene therapy, which aims to patch faulty genes with working DNA, has been a long time in development. The following are major milestones:

1972 - Researchers first suggest gene therapy as a treatment for genetic diseases but oppose its use in humans "for the foreseeable future", pending greater understanding of the technology.

1990 - A four-year-old girl with severe immunodeficiency became the first patient to undergo gene therapy in the United States.

1999 - American patient Jesse Gelsinger dies following a gene therapy experiment, setting the field back several years as U.S. regulators put some experiments on hold.

2002-03 - Cases of leukaemia are diagnosed in French children undergoing gene therapy in a further blow to the field.

2003 - The world's first gene therapy is approved in China for the treatment of head and neck cancer.

2007 - Doctors carry out the world's first operation using gene therapy to treat a serious sight disorder caused by a genetic defect.

2012 - Europe approves Glybera, the first gene therapy in a Western market, for an ultra-rare blood disorder.

2016 - Europe approves Strimvelis for a very rare type of immunodeficiency.

2017 or 2018 - The first gene therapy could be approved in United States. (Reporting by Ben Hirschler; editing by David Stamp)