'It totally backfired': The pitfalls of Alzheimer's genetic testing

Wendy Nelson watched her mother slowly die of Alzheimer's disease, unable to move or swallow at the end. "All her pleasures of life were gone," Nelson said.

Grief-stricken, terrified of facing the same death, Nelson ordered 23andMe(ME.O) DNA test kits for Christmas 2020 for herself and three adult daughters.

A Boston-based biotech executive who is now 52, Nelson hoped the kits would provide reassurance. They delivered the worst possible result. Nelson has two copies of the APOE4 gene variant that increases the risk of Alzheimer's, which means her risk of...