T-cells

A rare genetic disorder that transforms a person's hands and feet, in particular, into tree-bark-like warts and cutaneous horns made news recently. It's truly out of the ordinary. So what's this all about? 
A drop in T-cell production may mean that astronauts are at least temporarily immunocompromised by space flight. To those of you who are eager for a trip to Mars, add "immunosuppression" to your list of concerns.