Credit: Tami Tolpa

The discovery late last year of a way to generate stem cells from adult skin cells could allow scientists to study disease in unprece­dented detail, from earliest inception to final biochemi­cal demise. That's because the stem cells could be used to develop cell lines derived from people with a given disease--neurons from Alzheimer's patients, for example, or blood cells from people with sickle-cell ­anemia. The resulting trove of cells would capture all the genetic quirks of these complex diseases.

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