Discovery of cells that keep immune responses in check wins medicine Nobel Prize

Today, finding a mutation on the X chromosome would be relatively easy. But in the 1990s, it was a labor-intensive effort. After narrowing the mutation’s location down to a stretch of 500,000 nucleotides that included 20 genes, they carefully scanned 19 of them before finding a mutation in the very last one; it was a small, two-base pair insertion that threw the coding out of frame and resulted in a stunted protein. The mutated gene hadn’t been studied before, but it looked like…