The Genetic Signature of Diseases Revealed in Simple Urine Specimens

By L.David Tomei, Ph.D. CEO and founder Xenomics Inc.

October 9, 2006

(HealthNewsDigest.com).. We often hear about the discovery of genes that may be linked to diseases of various kinds. It is always tacitly assumed that a laboratory test can be performed to detect the presence of such disease-linked genes, by simply drawing blood from a patient, taking a biopsy or performing amniocentesis, or just collecting a sputum specimen. However, everyone is also aware that these specimens are not only invasive, but samples themselves are considered biohazards, as evidenced by the fact that extraordinary safety measures are taken to prevent both the patient and healthcare workers from being exposed to the specimens. So how it is possible to safely obtain a specimen that contains the genetic DNA markers needed to detect various diseases from patients? From the view of the clinics and testing laboratories, how can specimens be obtained that are less costly to handle and analyze, yet provide access to the genetic DNA that may exist in the body and mark the presence of disease? It turns out the answer is to let the body itself prepare the safe, non-hazardous lab specimen which is what the kidneys do every second of the day.

Why is it so important to be able to sample and monitor the genetic information circulating through the body? Many of us know by now that the genetic makeup of your body consists of DNA, and great advances in the Human Genome Project have actually revealed the genetic code itself, which defines every feature of our bodies. Genetic testing is an important area of science and medicine that strives to discover the particular genetic codes that suggest for instance that the person is susceptible to particular diseases during their lifetime. However, the genomes of many other living things also have been defined, and a new field of diagnostics is about to emerge; one based on the detection of DNA that is alien to the body.

Each organism that can cause infectious diseases such as viruses and bacteria has its own genome comprised of the same material of which our own genome is made. Many of these organisms have their genome sequenced and their genetic code is becoming increasingly well defined. Gene-based diagnostics today utilize this information to search for tell-tale genetic fragments that are in our bodies, revealing the presence of the disease causing agents with precision and sensitivity previously unattainable. During the past decade there have been great advances in DNA technology that now enable laboratories to detect even single molecules with an exactness that goes beyond the very best tests in wide use today. It is now possible to detect the presence of a few infectious organisms in the entire body based on their unique DNA signature.

The detection of diseases through unique genetic signatures is not limited to the agents that cause infection. Almost every week we read in the press that a new gene is linked with cancer, or even a particular type of tumor, and it is clear that we are approaching a time when it will be possible to detect tumors at their very earliest stage of development, helping make anticancer therapy more effective.

It is also important to examine the breadth of diagnostic applications that have become accessible. For example, fetal DNA appears in the circulation and urine soon after conception and carries with it information regarding the gender of the fetus as well as the presence of serious genetic anomalies. Today only hazardous and highly invasive procedures such as amniocentesis can access this DNA for analysis. Safe and effective options for early detection of genetic anomalies will be available in the very near future.

Another field of medicine that has received much attention is stem cell transplantation. Stems cells have their own distinct genetic signature, as do any transplanted tissues and organs from the genetic makeup of the donor. It is now possible to follow the fate of transplanted cells in the recipient by following the appearance of the donor genetic markers as they appear in the blood and urine. In the instances of organ transplantation, it will be possible to monitor the health of the transplanted organ by following the appearance of the donor gene markers in simple urine specimens, instead of biopsies or even repeated blood samples.

A significant advance was introduced when it was shown that DNA markers were purified through the kidneys and appeared in relatively simple form in urine. Essentially, this discovery demonstrated that the kidneys perform DNA extraction from blood every second of the day, and urine specimens can be viewed as having DNA fragments from throughout the body, including those from anything that is genetically foreign. This advance is important to patients who deserve access to the advances made in genomics, but also to testing laboratories who must contend with biologically hazardous blood and tissue specimens that are significantly more complex and costly to analyze, as compared with a small urine specimen.

Advances in science and medicine are not always complex; some are basic and simple, yet have the potential to greatly impact healthcare. The elegance of the most advanced techniques in DNA analysis was recently complemented by the seemingly mundane discovery that DNA genetic markers from throughout the body are purified by the kidneys and appear in simple urine specimens. This new approach to more simple and safe methods of obtaining specimens for highly precise gene-based diagnostics makes the benefits of recent advances in genomic research accessible to patients and physicians alike.

Copyright © 2006 by HealthNewsDigest.com.

This article posted November 12, 2006.