Earlier this year, Steve McCarroll announced that his team had discovered the gene that most powerfully drives our risk of schizophrenia. Known as C4, it was previously viewed as an immune-system gene, but clearly, it also does something in the brain. To work out what, McCarroll first needed to know which cells in the brain activate C4.
Easier said than done: “There's no place for looking that up,” he says. Instead, his team had to examine slices from over 700 postmortem brains, and stain them with a dozen different-colored antibodies that recognize C4. “The slices were variable in quality. The antibodies were variable in quality. It took us almost a year to get satisfying answers. It was a slog.”
McCarroll's lament is a common one. Geneticists are constantly learning about genes that influence our risk of disease, but genes don't perform in a vacuum. They perform in our cells. And since the 30 trillion cells in your body all share the same genes, you need to know which cells are actually using the gene in question. Where are those cells? What do they do normally, and what goes wrong in cases of disease? And in most cases, without the kind of slog that McCarroll endured, the answers are: we don't know; no idea; and, ¯\_(ã??)_/¯.
