When Bonnie J. Rough receives the test results that confirm she is a carrier of the genetic condition hypohidrotic ectodermal dysplasia, or H.E.D., it propels her on a journey deep into her family's past in the American West.
At first glance, H.E.D. seems only to be a superficial condition: a peculiar facial bone structure, sparse hair, few teeth, and an inability to sweat. But a closer look reveals the source of a lifetime of infections,...