A Case Too Soon for Genetic Testing?

The raison d'être behind genetic screening is that genotype predicts phenotype (disease risks). But it isn't always so. The likelihood of a specific mutation in the BRCA1 gene causing breast cancer, for example, depends on one's ethnic group. Now a study raises questions about what looked like a perfect candidate for population genetic screening: hereditary hemochromatosis (HH), a form of "iron overload" disease.1 Standard biochemical testing appears to be a better predictor than gene tests.

Ricki Lewis
Apr 1, 2002
The raison d'être behind genetic screening is that genotype predicts phenotype (disease risks). But it isn't always so. The likelihood of a specific mutation in the BRCA1 gene causing breast cancer, for example, depends on one's ethnic group. Now a study raises questions about what looked like a perfect candidate for population genetic screening: hereditary hemochromatosis (HH), a form of "iron overload" disease.1 Standard biochemical testing appears to be a better predictor than gene tests.

"Our findings really shake the boat of conventional thinking about hemochromatosis, and are understandably disturbing to self-help groups pushing for universal genetic, as opposed to biochemical, screening," says Vincent J. Felitti, recently retired chief of preventive medicine at Kaiser Permanente in San Diego and co-director of the investigation. And the fate of the HH gene test may influence implementation of other genetic tests.

The problem for HH is statistical: Most people who have...

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