Table 3.

CDC evidence-based classification of genetic and genomic tests and selected examples

Tier	Evidence for recommendation	Examples
Tier 1	Supported by a base of synthesized evidence for implementation in practice	HBOC, Lynch syndrome, newborn screening, FH
Tier 2	Synthesized evidence is insufficient to support routine implementation in practice; may provide information for informed decision making	Many pharmacogenomics tests
Tier 3	Evidence-based recommendation against use; or irrelevant synthesized evidence identified; not ready for routine implementation in practice	Direct-to-consumer personal genetic tests

CDC, Centers for Disease Control and Prevention; FH, familial hypercholesterolemia; HBOC, hereditary breast and ovarian cancer.