Practice standards in medical genetics provide an implicit guide to the eth
ical, legal, and social implications (ELSI) of genetic tests. The common us
e of nondirective counseling reflects the principle that many testing decis
ions should be determined by personal values. Yet geneticists make test rec
ommendations in some circumstances, e.g., RET mutation testing for MEN2 and
newborn screening for phenylketonuria (PKU). Conversely, many geneticists
recommend against testing for Apolipoprotein E (ApoE) alleles to predict Al
zheimer disease (AD) risk. Taken together, these examples suggest that gene
tic tests can be categorized by a joint consideration of clinical validity
and availability of effective treatment for persons who test positive. For
genetic tests with high clinical validity/no treatment (e.g., presymptomati
c testing for Huntington disease), the predominant concern is adequate nond
irective counseling to ensure an informed autonomous decision. By contrast,
the predominant concern for tests with high clinical validity/effective tr
eatment (e.g., PKU) is assuring access to care for eligible persons. For te
sts with limited clinical validity/no treatment (e.g., ApoE), recommending
against test use can be justified on the principle of avoiding harm. For a
fourth category, tests with limited clinical validity/effective treatment (
e.g., HFE mutation testing for hereditary hemochromatosis), net benefit is
the issue: the balance between potential benefits of treatment and potentia
l harms of genetic labeling must be weighed. Where uncertainty exists conce
rning both clinical validity and effectiveness of treatment, as in the case
of BRCA1/2 mutation testing, the value of testing may vary according to di
fferent testing contexts. This approach to test categorization allows a rap
id determination of the predominant ELSI concerns for different kinds of ge
netic tests and identifies the data most urgently needed for test evaluatio
n. (C) 2001 Wiley-Liss, Inc.