More than a dozen people who have had their genomes sequenced stand on stage in an R&D center near Boston. Billed as the last time all such people might fit in one room before the technology moves into the mainstream, the event doesn't quite include the whole group: actress Glenn Close and South African archbishop Desmond Tutu, among others, didn't make it. But those who did include James Watson, codiscoverer of the structure of DNA; Harvard historian Henry Louis Gates Jr.; entrepreneur Esther Dyson; and a smattering of leaders from gene-sequencing companies.

Leaning against a wall at one end of the stage is James Lupski, a pediatrician, clinical geneticist, and scientist at Baylor College of Medicine. Unlike many of the others, Lupski wasn't interested in sequencing as a way to trace his ancestry or determine his future likelihood of developing some ailment. Instead, he had hoped to solve a medical mystery that affects him in the most personal way: the cause of a genetic disorder, called Charcot-Marie-Tooth disease, that struck him and several of his siblings as teenagers, severely weakening the muscles in their legs and feet. After a quarter-century searching for the gene responsible, the 53-year-old scientist finally found it by scouring his own genome, combing through the billions of DNA building blocks represented by the letters A, T, C, and G. It marks the very first time that whole-genome sequencing--determining the exact order of all the letters in an individual's DNA--has identified the mutation to blame for a specific case of a genetic disease.