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Residual risk is the percent chance of still carrying a variant after genetic testing is negative.
- In many cases, genetic testing is not absolute (that is, it's not 100 percent sensitive).
- Therefore, even if your genetic testing is negative, there remains a residual chance of carrying a variant.
- In the above example, even though Mary's cystic fibrosis carrier testing is negative, her residual risk to be a carrier of cystic fibrosis is about 3 percent.
- If Mary did not have any family history of cystic fibrosis, her likelihood to carry a variant in CFTR would be reduced to less than 1 in 200 or less than 0.5 percent with normal carrier testing.