So, for instance, [the science of] molecular diagnostics allowed the doctors to reach a [molecular] diagnosis ?
- Diagnostics is the theory and science of discovering the nature of an illness. E.g. The students has an exam in diagnostics.
- A diagnosis is a single decision by a doctor, as to the nature of an illness. E.g. Dr Smith's diagnosis was that she had angina. (Plural: diagnoses)
- To diagnose is the verb. E.g. The doctors were unable to diagnose my problem.
- Diagnosing is the present participle of the verb, but also a noun. E.g. Diagnosing meningitis is difficult.