PARIS, July 5 (AFP) - A new gene treatment, successfully used on mice,
offers hope for millions of people in the Mediterranean, Asia and the United
States who suffer from potentially fatal forms of anaemia.
Writing in Thursday's issue of the British science weekly Nature, a team of
American doctors say the therapy involves replacing a faulty gene blamed for
causing beta-thalassaemia and sickle-cell anaemia.
Beta-thalassaemia -- Greek for "sea blood" -- is so called because it was
first discovered among people around the Mediterranean Sea, where incidence of
it, especially in Cyprus, is high. Thailand is among countries in Asia where
this form of anaemia is common.
The condition is caused by an inherited flaw in a gene that turns out vital
amino acids which are used to make haemoglobin, the oxygen-carrying protein in
red blood cells.
The gene is also to blame for a related disease, sickle cell anaemia, that
strikes about one in 400 black Americans, in which the normally disc-shaped
red blood cells shrivel to sickle shapes, unable to take sufficient oxygen to
the vital organs. Chronic fatigue, pain and death can result.
The therapy entails using a disarmed virus called a lentivirus as a Trojan
horse, infecting cells with a copy of the right gene and a large section of
DNA that is used by the gene to carry out its functions.
The gene was inserted in mouse stem cells -- the cells that are created at
the very earliest stages of an embryo and go on to develop into any of the
body's organs.
The mice's bone marrow cranked out healthy haemoglobin, "sufficient to
ameliorate anaemia and red cell morphology," the researchers say.
"Such levels should be of therapeutic benefits in patients with severe
defects in haemoglobin production," they add.
The work was carried out by a team led by Michel Sadelain of the Memorial
Sloan-Kettering Cancer Center, New York.
The research is the latest in a small but fast-growing field in which
scientists hope to cure inherited diseases by either blocking the working of a
flawed gene or -- more ambitiously -- knocking it out and replacing it with a
properly functioning one.
This latter approach is controversial. Relatively little is known about how
genes interact in the complex business of producing proteins, the body's
workhorse substance.
There have been several setbacks in gene replacement therapy, including the
death of an 18-year-old US patient who was being treated for a rare liver
disease among males.
On the other hand, French doctors earlier this year announced a stunning
success in replacing a gene that caused chronic immune deficiency among
so-called "bubble babies" forced to spend their lives in sterile plastic tents
to avoid infection.
