Before a physician can prescribe pills or recommend a therapy, the patient must be diagnosed. Diagnosis plays an important role in clinical decision-making. False positives or otherwise inaccurate results may lead to improper or even harmful care. By obtaining a correct diagnosis, physicians are able to narrow down their options and select the most effective treatment plan for the patient, increasing the probability of a better outcome. Even when a diagnosis is correct, other factors must be taken into consideration. Cancer, for example, is not a one-size-fits-all disease. Lung cancer comes in several different varieties: non-small cell carcinoma, squamous cell carcinoma, adenocarcinoma, broncho-alveolar carcinoma, and more. The treatment that defeats one type of cancer may be ineffective against another. Then, too, each patient is different. One cancer patient may respond well to a particular therapy, while another patient with the same disease just grows sicker. Companies such as Clarient are developing diagnostic tests that address the individual differences between each patient. Clarient offers a gene mutation test to help physicians select the best treatment for patients with non-small cell lung cancer, the most common form of lung cancer. Nearly all patients who respond well to tyrosine kinase inhibitor therapies such as gefinitib and erlotinib have mutations in the EGFR gene. A number of companies are developing diagnostic tests with the goal of guiding physicians toward more informed clinical decisions: For psychiatric patients, finding the right treatment is often a process of trial and error. Psychiatrists typically have little more to go on than the patient’s subjective, self-reported symptoms. California-based CNS Response has compiled a biomarker database that helps predict patient response to psychiatric drugs. The company can provide reports to aid physicians in developing personalized treatment plans for each patient. RedPath Integrated Technology, based in Pittsburgh, offers DNA analysis of tumors that have been diagnosed “indeterminate.” The PathFinderTG platform was developed over 17 years and has been validated in over 100 peer-reviewed articles. The test can be used on a variety of organs, cancers and sample types. Cambridge Heart of Tewksbury, Mass., measures subtle heartbeat fluctuations to identify patients who are at risk for sudden cardiac death. By knowing a patient’s risk, physicians may be better equipped to develop a preventive plan that can save the patient’s life. DiagnoCure isn’t just interested in the early diagnosis of cancer, but in the management of the disease. The Canadian company uses molecular diagnostics to analyze genetic behavior in prostate, colorectal, breast, bladder, and other cancers. While finding the correct treatment requires an accurate diagnosis, factors such as disease management, health monitoring, and accurate patient records are also important to quality of care. When combined, these elements can interconnect in a way that treats the patient not as a collection of symptoms and diseases, but as a unique individual with their own personal health signature.