Ring Finger Length Linked to ALS, Study
MONDAY, May 9 (HealthDay News) -- Having long ring fingers has
been associated with a lethal nervous system disease known as
amyotrophic lateral sclerosis (ALS), British researchers
Researchers hasten to explain, however, that this does not mean
people with long ring fingers will develop the disease -- or even
that they are at higher risk for it.
"We have not done a study that shows the risk of subsequently getting ALS in people with long ring fingers," cautioned lead researcher Ammar Al-Chalabi, a professor of neurology and complex disease genetics and director of King's MND Care and Research Center at King's College London.
What the study does find, Al-Chalabi said, is that "people with
ALS tend to have more 'male' hands in that the ring finger is
relatively longer than the index finger -- something that is a
tendency in men."
"We already know that ALS is commoner in men, but this might suggest that the reason is something to do with the balance of hormones we are exposed to in the womb, because finger length seems to be determined in part by the amount of male hormone a developing baby is exposed to," he added.
ALS, sometimes called Lou Gehrig's disease, is a rapidly moving
disease that is always fatal. Although it tends to leave people's
intelligence intact, it attacks nerve cells in the brain and spinal
cord that control voluntary movement, causing progressive weakness
Most people with ALS die within three to five years, although
about 10 percent live 10 years or longer with the disease,
according to the U.S. National Institutes of Health. When muscles
in the chest fail, patients cannot breathe without ventilation and
most eventually die from respiratory failure.
The cause of ALS isn't known. Although it can run in families,
it strikes at random, and there is no cure.
The report was published in the May 9 online edition of the
Journal of Neurology, Neurosurgery and Psychiatry.
For the study, Al-Chalabi's team used a digital camera to
photograph hands and finger length of 110 people, some with ALS and
others without the disease.
The investigators then looked at the ratio of the length of each
person's index finger to ring finger -- called the 2D:4D ratio. The
ratio is calculated by dividing the length of the index finger of
the right hand by the length of the ring finger.
A low ratio indicates the ring finger is relatively long
compared with the index finger. Scientists believe that this
finger-length ratio is a marker of high prenatal testosterone
levels. It is most likely the reason that men have longer ring
fingers than index fingers, while women don't, the researchers
The researchers found that 2D:4D ratio was lower for people
suffering from ALS, compared with those without the disease.
"The relative lengths of our fingers provide a clue as to what makes motor nerves vulnerable," Al-Chalabi said. "It looks like male hormones in the womb not only make our nervous systems and muscles more masculine, they might also make them more at risk of ALS."
He and the other researchers stressed, however, that the digit
ratio "has no use as a screening tool."
Commenting on the study, Dr. Michael Geoffrey Benatar, an
associate professor of neurology at the University of Miami Miller
School of Medicine, said that "the idea that some early event in
life makes one's susceptibility to a neurodegenerative disease is
not an unreasonable idea at all."
The context of this notion is that it is not known what puts
people at risk for ALS, he said. Whether or not finger size is
really connected to the risk of ALS remains to be seen, Benatar
"I don't think one can take finger measurements and say 'you're at risk or you are not at risk,' but the idea that this might represent a biological marker is an interesting observation and warrants further study," Benatar said.
For more information on ALS, visit the
U.S. National Institute of Neurological Disorders and
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