TIMELINE-Milestones in gene therapy

April 27 (Reuters) - Gene therapy is making a comeback, with a flood deals, stock market debuts and increased investment by big pharmaceutical companies.

But it remains a risky field, as highlighted by the failure of an experimental heart treatment from Celladon in a clinical trial, announced on Sunday.

The following is a timeline of developments in the technology, which uses viruses to patch faulty genes with working DNA:

1972 - Researchers first suggest gene therapy as a treatment for genetic diseases in a paper in the journal Science but they 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 key experiments on hold.

2002-03 - Cases of leukaemia are diagnosed in French children undergoing gene therapy for genetic immunodeficiency 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 - British 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 the first gene therapy in a Western market to treat an ultra-rare blood disorder.

2014 - Gene therapy shows promise in clinical trials for inherited blood disorders, certain types of progressive blindness and HIV.

Reporting by Ben Hirschler, editing by Louise Heavens