Should be biologic marker be sensitive and specific?

Potential biologic markers in psychiatry are often subjected to tests of sensitivity and specificity. However, in many instances, clinically diagnosed diseases may not be truly singular in their pathophysiology, and these tests may be inappropriate. One may distinguish between diagnostic markers useful in clinical pathology, linkage markers specifying genetic location and pathophysiologic markers that are primarily valuable as research tools. The latter are probably most useful in present-day psychiatry but they may not be sensitive or specific in their correspondence to clinical diagnosis.