Beastly gene

-- (Credit: Arvind Yadav /CSE)Myths can sometimes be closer to reality the
one would suspect. For instance, in Europeao
folklore one finds mention of creatures called
werewolves, who are described as peopoo
who can change into wolves, with hair as
over the body and face. However, there rs a
human disorder called the
congenital generalised
hypertrichosis that produces a similar state. Now,
scientists in America have
traced the reason behind
this rare hereditary condition that results in a furry
appearance since birth to
the presence of a mutant gene.
Scientists believe that
the hairy condition in
humans might be an example of an atavistic mutation
- the reemergence of an
evolutionarily ancient trait
that is normally kept supressed. The disorder
reminds one of the original mammals covered from head to toe with
a protective fur coat, and which condition
was lost for some reason by the modern man.

In hypertrichosis, the only parts of the
patient that remain free of hair are the
palms of the hand and the soles of the
feet. In humans with hypertrichosis, even
the cheeks, neck and eyes, which lack fur
in apes like chimpanzees and gorillas, are
not spared. This suggests that the gene
recalls something earlier than the emergence of hominoid apes abotit 25 million
years ago.

Remarks Brian K Hall, a development
biologist at Dalhousie University in
Halifax, Nova Scotia, "Atavistic mutations
tell us that a lot of information is kept
around for a very long time. Just because
an animal isn't using a gene anymore
doesn't mean the information just disappears." But Jose M Cantu, head of genetics at the Mexican Institute for Social
Security in Guadalajara warns that the
atavistic mutation is only a theory for
speculation.

The precise gene resulting in
generalised hypertrichosis is not
known yet, but is located somewhere on the bottom half of the
X-chromosome. Researchers
found this location by studying
the genetic material of members
of a large Mexican family who
may be the only human representatives of
this particular mutation.

Being an X-linked trait, the
gene finds its
fullest expression
in males. Females with the condition inherit only
one copy of the mutant X-chromosome,
with the normal copy of the
other X-chromosome offering
partial protection against the disorder.