Too many health care providers, critics say, have not educated themselves about the genetic tests that could benefit their patients.

Others, pressed for time, simply do not communicate what can be complex information. And some choose not to inform their patients of certain tests they have deemed inappropriate, in effect making a value judgment about abortion, disabilities and risk that patients say they have a right to make for themselves.

A growing number of patients say the lack of basic information about DNA tests is altering lives in each of the three areas where the tests are available: prenatal screening, newborn screening and screening for some cancers and other adult diseases. Even if they decide not to use the new technology because of expense or personal values, they say, they should have the choice.

One basic problem, health care experts say, is that doctors who did not learn genetics in school must now make time to educate themselves. Last week, the federal Centers for Disease Control and Prevention released a study that found that only 52 percent of health care providers in five United States cities knew that the major mutations for breast cancer could be inherited from either parent.