Mapping the Breast Cancer Gene

Genes have been implicated in breast cancer occurrences for a very long time.

BRCA1 and BRCA2 have been identified and studied. New genetic variations that effect the body’s use or production of estrogen are popping up on a regular basis.

A review of basic genetics explains why this is so important. Humans have 23 chromosome pairs. Each chromosome is a chain of genes linked together.

Each human gene is made up of a series of chemical building blocks (DNA) represented by letters. A (adenine), T (thymine), G (guanine) and C (cytosine). They control the production of the proteins that our body uses to build cells, organs and systems. The number and order of these letters or bases determine what we look like, and the diseases which we may be genetically predisposed to getting.

Mapping any human chromosome is an incredibly complex project. It is estimated that there are approximately 80,000 genes making up our chromosomes. Genes range in size from 1,000 to 583,000 bases of DNA.

The first chromosome to be deciphered was completed in December 1999. Chromosome 22 was used because it is one of the smaller strands. According to the researchers, “A total number of at least 545 genes and 134 pseudogenes (genes that once functioned but no longer do) were detected on the chromosome, with 200 to 300 additional ones likely.” And that’s a small chromosome.

The study of DNA from breast cancer patients should shed light on which genes or sequences of genes are involved with changing normal tissue into tumors. The fact that all women are exposed to estrogen and other hormones that increase the chances of developing cancer, but not all women get breast cancer means that there are some individual responses that are different. If the DNA analysis can isolate which genetic structures are responsible, that would be a giant leap forward in the study of this disease.

March 27, 2000

Last updated March 31, 2006

Elsewhere on the Web:

Breast Cancer Gene Database
Cancer hope over breast gene find
Imaginis - Genetic Risk Factors for Breast Cancer