Int'l team identifies ALS gene
Discovery will help provide families with genetic counselling, could lead to better understanding of why nerve cells break down.
DNA Photo: Thinkstock/Imagebank
An international research team that includes doctors at Tel Aviv’s Sourasky
Medical Center has discovered an additional defective gene that causes
amyotrophic lateral sclerosis (also known as Lou Gehrig’s disease or motor
The discovery will help provide families with genetic
counselling and could lead to better understanding of why nerve cells break down
and eventually, to treatments for the incurable and fatal neurological
Only three out of every 10 cases of ALS are the result of family
genetics; 70 percent of patients develop sporadic ALS, which is not connected to
an inherited gene.
The discovery was published on Sunday night in the
latest issue of the prestigious journal Nature. The head of the multi-center
study was Prof. Robert Brown of the University of
Nevertheless, said Prof. Vivian Drory of Sourasky’s
neurology department and ALS clinic, and Tel Aviv University’s Sackler School of
Medicine, insight into genetically inherited ALS will increase knowledge of the
sporadic cases as well, as the mechanism is similar. Until recently, scientists
though that 90% of ALS cases were sporadic, and only 10% genetically
Drory told The Jerusalem Post that the Israeli family members
she investigated are of Sephardi origin, and that some of them have already died
of the disease. As a result of the discovery of the gene, which is called
profilin1, other Israeli families with ALS will also be
Hospitals around the country diagnose some 120 to 140 new cases
a year, and specialists are in the process of testing their genome to determine
whether they have the sporadic or inherited disease.
Drory noted that the
gene discovery was not a breakthrough, but added a piece to the ALS puzzle that
could lead to better genetic counseling and eventually a treatment.
is another step forward,” she said. “We still have a long way to go.”
is the first time Israelis have been involved in identifying a defective gene
ALS is a disease of the nerve cells in the brain and spinal cord
that control voluntary muscle movement. Gehrig, the famous American baseball
star, apparently suffered from the sporadic type, as no members of his family
were know to have it, said Drory.
In ALS, nerve cells – neurons – waste
away or die and can no longer send messages to muscles. This eventually leads to
muscle weakening, twitching and an inability to move the arms, legs and body.
The condition worsens progressively. When the muscles in the chest area stop
working, it becomes hard or impossible to breathe on one’s own, although the
brain continues to function normally. ALS affects approximately two out of every
100,000 people worldwide.
Symptoms usually do not develop until after age
50, but they can start in younger people.
Persons with ALS experience
gradual loss of muscle strength and coordination that eventually makes routine
tasks – such as climbing stairs, getting out of a chair or swallowing –
impossible. Muscles used in breathing or swallowing may be the first muscles
affected. As the disease gains ground, more muscle groups develop
Many patients die within 10 years, but less commonly, the
progression of the disease halts, although at a debilitating stage. Such is the
case of UK theoretical physicist Prof.
Stephen Hawking, who is already 70
years old and able to communicate only by looking at a special computer that
synthesizes a voice and moves a cursor.
The defective genes that were
discovered in the last decade, mostly in the US and all involved in familial
ALS, include CDP43, FUS, VCP and ubiquilin. They involve the building of the
skeleton of the neuron; when the cytoskeletons are not adequately constructed,
ALS results. One defective gene is enough to cause the illness, said
As ALS victims are diagnosed when they are adults – even
middle-aged – they are old enough to have children to whom they can pass on the
familial type of disease.
Now that the profilin1 gene has been
identified, genetic counseling can be provided to couples and pre-implantation
genetic diagnosis (PGD) can be performed to determine which embryos have the
defective gene, and thus prevent their implantation through in-vitro
Couples who carry the gene, however, are not advised
against getting married.
ALS occurs in all populations, and is not more
prevalent among Jews.
Even if identical twins have the defective genes
that cause ALS, they will not necessarily develop it at the same
One, said Drory, could get it at 40, and the other at
“Genetic penetration by the gene is not uniform,” she said.