It's in the Genes
Dateline: 06/11/98
One of the problems with using animal models concerns the exact nature of the physical, anatomical, and pathological features of disorders in humans. While animals such as rats and mice have proved useful due to the similarity of major systems, some human disorders, such as cardiomyopathy, don't have direct animal models. Scientists took a big step in alleviating the absence of animal models by producing a transgenic mouse that displayed the pathological, anatomical, and clinical manifestations of the early stages of cardiomyopathy.
Cardiomyopathy--hmmm, remember the Bio-Word article--effects some four to five million Americans and is a direct cause of congestive heart failure. For older Americans, heart failure is both a leading cause of death and hospitalization. While the disease has been associated with infections and alcohol abuse, the cause is unknown.
There does seem to be a genetic predisposition to cardiomyopathy. Recent studies have indicated that almost 45 percent of patients diagnosed have another member of their family with a similar condition.
In cardiomyopathy the heart muscle continues to expand and consequently weaken. Circulation to important organs is thus impaired which can lead to the failure of a variety of systems. Patients experience many symptoms, such as lightheadedness, fatigue, and shortness of breath. The disease is hard to detect in its early stages and most research has focused on the later stages. With the advent of the transgenic mouse, researchers are optimistic that studying the early stages of the disease will result in an effective treatment or a possible cure.
To create the mouse, scientists altered the CREB (a gene active only in the heart) into a mutant form. This led to a cascade effect since CREB is involved in the regulation and growth of several other genes that control heart muscle development. The altered mice are normal at birth but develop cardiomyopathy over time.
The resulting clinical, anatomical, and pathological changes in the diseased mice closely resemble the changes that occur in humans even on the microscopic level. Like their human counterparts, the mice develop heart failure and die prematurely.
What do you think? How might transgenic animals be used to treat a variety of other diseases? Come over to the Biology Forum and share your thoughts, opinions, and feelings. 'Til next time...
