Medicine's 'Genaissance'

By Sharrer, G. Terry | The World and I, May 2000 | Go to article overview

Medicine's 'Genaissance'


Sharrer, G. Terry, The World and I


Innovative microscale analyses and novel techniques for gene repair offer the unprecedented opportunity to detect and correct genetic defects that are specific to individual patients.

Color, rubor, dolor, tumor (heat, redness, pain, and swelling)--the cardinal signs of inflammation that Aulus Cornelius Celsus taught in the first century a.d.--provided a focus for medicine that continued through the next two millennia. Over time, physicians sorted out diseases, developed diagnostics, and found effective remedies, but proficiency in healing was largely related to overcoming symptoms. Medicine's future, however, holds a new dimension, one dealing with the origins of disease--more precisely, specific versions of particular disorders, which may vary from individual to individual.

The energizer for this new approach has been the Human Genome Project's attempts to discover not only all the genes of our species but even the "single-nucleotide polymorphisms" (SNPs) that distinguish one person's genome from another's. With the discovery that many diseases arise from genetic defects, public attention has converged on the associated genes. But SNPs have drawn less notice, partly because their role in illnesses is not entirely clear.

SNPs are variations in the individual units (nucleotides) of the overall DNA structure. They occur about once in every 1,000 nucleotides of sequence, which means that there are conceivably 3 million SNPs in the human genome. Not even identical twins have identical SNPs. Most of these variations are in "noncoding regions," where the DNA sequence carries no instructions for protein synthesis. But some appear to be distantly linked to functional genes, and others are located within functional genes, where they may or may not exert a detectable influence. An example of an SNP with functional consequence would be a point mutation in a gene that leads to a disease.

One disease, various mutations

The genetics of colon cancer illustrates this specificity. About 95 percent of colon cancer patients have an adenocarcinoma (a type of tumor) in the colon, and nearly all of them have mutated genes on at least chromosomes 3, 5, 12, 17, and 18. These mutations began accumulating in a single cell that started the abnormal growth. Within each of those genes, however, hundreds of different point mutations are possible, causing functional changes. Each patient's repertoire of point mutations is distinct if not unique, leading to the inference that there may be nearly as many forms of colon cancer as there are people with that disease.

For diseases such as cystic fibrosis (CF), where the disorder is linked to a single defective gene, there is a mutation in the same nucleotide in many cases, but not in others. As a result, there is considerable diversity among those who ail from the same CF symptoms. Furthermore, SNPs have been implicated in such areas as susceptibility to infections, reaction to drugs, and even daily nutritional requirements.

It's ambitious to assume that all diseases can be subdivided into small groups, down to even individual expressions. In the nineteenth century, germ theory did something similar: It classified pyrexias (fevers) according to different causative pathogens. But will a medical approach that repairs genes ever be customized for individual patients? So far, expectations have outpaced results.

Microscale diagnostics

The surge in expectations is buttressed by remarkable innovations in diagnostics. Researchers have already developed microarray machines in which thousands of discrete DNA sequences are attached to glass chips [see "Genes on a Chip," The World & I, September 1997, p. 189]. In the foreseeable future, the entire human genome might be represented on a single chip. The strategy is that DNA fragments would be isolated from an individual, tagged with a fluorescent label, and tested for specific binding (hybridization) to complementary sequences on the chips. …

The rest of this article is only available to active members of Questia

Already a member? Log in now.

Notes for this article

Add a new note
If you are trying to select text to create highlights or citations, remember that you must now click or tap on the first word, and then click or tap on the last word.
One moment ...
Default project is now your active project.
Project items

Items saved from this article

This article has been saved
Highlights (0)
Some of your highlights are legacy items.

Highlights saved before July 30, 2012 will not be displayed on their respective source pages.

You can easily re-create the highlights by opening the book page or article, selecting the text, and clicking “Highlight.”

Citations (0)
Some of your citations are legacy items.

Any citation created before July 30, 2012 will labeled as a “Cited page.” New citations will be saved as cited passages, pages or articles.

We also added the ability to view new citations from your projects or the book or article where you created them.

Notes (0)
Bookmarks (0)

You have no saved items from this article

Project items include:
  • Saved book/article
  • Highlights
  • Quotes/citations
  • Notes
  • Bookmarks
Notes
Cite this article

Cited article

Style
Citations are available only to our active members.
Buy instant access to cite pages or passages in MLA, APA and Chicago citation styles.

(Einhorn, 1992, p. 25)

(Einhorn 25)

1. Lois J. Einhorn, Abraham Lincoln, the Orator: Penetrating the Lincoln Legend (Westport, CT: Greenwood Press, 1992), 25, http://www.questia.com/read/27419298.

Cited article

Medicine's 'Genaissance'
Settings

Settings

Typeface
Text size Smaller Larger Reset View mode
Search within

Search within this article

Look up

Look up a word

  • Dictionary
  • Thesaurus
Please submit a word or phrase above.
Print this page

Print this page

Why can't I print more than one page at a time?

Help
Full screen

matching results for page

    Questia reader help

    How to highlight and cite specific passages

    1. Click or tap the first word you want to select.
    2. Click or tap the last word you want to select, and you’ll see everything in between get selected.
    3. You’ll then get a menu of options like creating a highlight or a citation from that passage of text.

    OK, got it!

    Cited passage

    Style
    Citations are available only to our active members.
    Buy instant access to cite pages or passages in MLA, APA and Chicago citation styles.

    "Portraying himself as an honest, ordinary person helped Lincoln identify with his audiences." (Einhorn, 1992, p. 25).

    "Portraying himself as an honest, ordinary person helped Lincoln identify with his audiences." (Einhorn 25)

    "Portraying himself as an honest, ordinary person helped Lincoln identify with his audiences."1

    1. Lois J. Einhorn, Abraham Lincoln, the Orator: Penetrating the Lincoln Legend (Westport, CT: Greenwood Press, 1992), 25, http://www.questia.com/read/27419298.

    Cited passage

    Thanks for trying Questia!

    Please continue trying out our research tools, but please note, full functionality is available only to our active members.

    Your work will be lost once you leave this Web page.

    Buy instant access to save your work.

    Already a member? Log in now.

    Author Advanced search

    Oops!

    An unknown error has occurred. Please click the button below to reload the page. If the problem persists, please try again in a little while.