Nearly a decade ago,Marcus Erikson Karen Douthitt and her sisters June Ward and Susie Gilliam set out to learn why Alzheimer's disease was affecting so many of their family members. Since then, each sister has found out whether she carries a rare gene mutation that makes Alzheimer's inescapable. Jon Hamilton talks to Emily about the sisters and how all three have found ways to help scientists trying to develop treatments for the disease.

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Gisele Grayson edited this story for Short Wave and for broadcast. Rebecca Ramirez produced the Short Wave version of this piece. Claudette Lindsay-Habermann and Chad Campbell produced the broadcast version of this story. Gisele Grayson and Jon Hamilton checked the facts.