Forging Stronger Diagnostic Links Between the Predisposition to Disease and Pre-Symptomatic Disease
Posted Jan 20 2010 12:00am
Genomic testing will sometimes reveal a genetic predisposition to disease for an individual. This is both a strength and a weakness of this laboratory diagnostic approach because the person most frequently does not suffer from the actual disease. By way of contrast, serum biomarkers reveal the presence of disease, sometimes in a very early stage but, of course, provide only an indirect view of the genome (see: Wellness, Preventive Medicine, and the Classic Disease Model). This early stage view of disease provided by biomarkers is sometimes referred to as the pre-clinical or pre-disease stage. An individual exists in a state of wellness until a disease, sometimes in its early stage, is diagnosed. Predictive medicine takes advantage of various clinical lab tests (genomic, proteomic, and biomarkers, for example) to determine where a person falls on this continuous spectrum of wellness and disease. We look to the field of preventive medicine to take advantage of the numerous therapies known to medical science to forestall the onset of a disease or ameliorate its effects once it begins to take hold.
One of the criticisms of genomic testing is that it assesses a consumer/patient's predisposition to disease rather than the presence of early overt disease. Positive genomic test results are frequently a call for watchful waiting until such time as the disease that has revealed itself in the genome begins to manifest itself clinically. It understandable that some physicians and healthcare consumers alike shy away from such testing in that no therapeutic intervention is usually available or warranted as the result of such testing. It would be useful to develop more reliable links or relationships between genomic tests that indicate a predisposition to a disease and defined set of biomarkers that may provide definitive evidence that the early clinical stages of a disease have become manifest and may be treatable.
The need for such links is patently obvious to all physicians. What perhaps may be less obvious is how such links can be developed and then communicated to physicians or even to consumers who may want to take advantage of the genomic testing via the web sites that provide these services. The answer to this question is that a comprehensive set of genomic diagnostic tables need to be published on the web showing how a positive genomic test result can be confirmed by the measurement of individual or sets of serum biomarkers, the latter known as IVDMIAs. For the sake of this discussion, I will refer to such tables as genomic-biomarker interpretation tables (GBITs). Perhaps a reader of this blog can come up with a more suitable name.
The development of such tables is easier said than done because of the wide array of genomic tests and biomarkers that are available in the clinical lab market. Moreover, biomarkers are being described almost on a daily basis but the vast majority of them have never been validated in a clinical setting. Hence, the information that would be provided in such tables will need to be constantly updated. Moreover, such tables also need to be extensively annotated by physicians and lab scientists in order to accurately present the strengths and weakness of any conclusions that can be drawn from the information. The question of exactly what type of organizations would be tasked with the development of such tables will be the subject of subsequent notes. The GBIT authors and maintainers obviously need to be physicians and scientists free of any commercial biases.