A Bellevue man, son of the co-discoverer of the structure of DNA, will auction off a letter his father wrote him about the breakthrough at an April 10 sale at Christie’s in New York.

Michael Crick was 12 and a student at a boarding school when his father, Francis, wrote to tell him about the discovery, which included a sketch of DNA’s double helix structure.

Michael Crick, now 72, said he knew his father had done something remarkable, but didn’t understand at the time its full impact. The letter was written about a month before the work, by Francis Crick and James Watson would be published.

Crick, Watson and Maurice Wilkins were awarded the Nobel Prize in Medicine in 1962 for their work.

Michael Crick said he will donate half the proceeds from the sale of the letter to a trust benefiting the Salk Institute, where his father later worked for several decades later in his life.

Michael Crick became a pioneer designer of computer games.