The team that created a firestorm
of controversy after successfully cloning Dolly the sheep is considering
helping a group of researchers at Edinburgh create a genetically engineered
sheep that has human cystic fibrosis.
Cystic fibrosis is a genetic
disease caused when a child receives a specific faulty gene from both
parents. Cystic fibrosis causes a variety of health problems, which tend
to vary from individual to individual, but is marked by severe respiratory
problems. People with cystic fibrosis have mucus secretions that are much
thicker and stickier than normal human mucus secretions, and the thick
secretions can cause severe respiratory problems from difficulty breathing
to higher risk of infection. A lot of advances have been made in extending
the life span of people with cystic fibrosis, but even today only 50%
of those with the disease will survive into their 30s (many of those patients
have to take up to 40 pills a day to prolong their lives).
Scientists have already managed
to create smaller animals, such as mice and rats, with cystic fibrosis,
but nobody has attempted to do so with larger animals. Sheep are a particularly
good candidate for cystic fibrosis research because they have lungs similar
to human lungs, and they tend to suffer from similar respiratory ailments.
The research under consideration would create at least two sheep with
the defective gene and then require breeding those sheep to produce a
sheep with a copy of the defective gene from each parent.
The Edinburgh researchers already
have a gene therapy treatment for cystic fibrosis that has received approval
in Great Britain for testing in normal sheep, and if those experiments
are successful an experiment in sheep that have the human disease would
be the next logical step.
References:
Dolly
team to create sheep with cystic fibrosis. The Times (UK), February
8, 2000.
What is cystic
fibrosis?. Michigan State University fact sheet.