Navigation
Hair Loss News Archives
September 2006
Hair-pulling Disorder Caused By Faulty Gene In Some Families
Scientists at Duke University Medical Center have identified gene mutations that
cause trichotillomania, a psychiatric disorder that triggers people to
compulsively pull their hair.
The disorder affects between 3 percent and 5 percent of the population and is
considered an impulse control disorder.
Patients with trichotillomania have
noticeable hair loss or patches of baldness, but they often mask their habit. As
a result, the disorder often goes undiagnosed and untreated, said researchers.
The relatively unknown disorder is often accompanied by other psychiatric
conditions, such as anxiety, depression, obsessive compulsive disorder or
Tourette syndrome, which are better known than the hair-pulling behavior.
The Duke team found two mutations in a gene called SLITKR1 that were implicated
in trichotillomania patients. The mutations account for only a small percentage
of trichotillomania cases, said the scientists.
However, their findings are significant because they validate a biological basis
for mental illnesses.
Such illnesses have long been blamed on a person's
upbringing or life experiences, said lead study investigator Stephan Z chner,
M.D., assistant professor of psychiatry and researcher at the Duke Center for
Human Genetics.
"Society still holds negative perceptions about psychiatric conditions such as
trichotillomania.
But, if we can show they have a genetic origin, we can improve
diagnosis, develop new therapies and reduce the stereotypes associated with
mental illness," Z chner said.
Currently, there is no specific treatment for trichotillomania, although it is
sometimes successfully managed with drugs used for depression and anxiety
disorders.
Results of this study will appear in the October 2006 issue of the journal
Molecular Psychiatry. The research was self-funded through Duke University.
The Duke scientists studied 44 families with one or more members who had
trichotillomania.
The researchers studied SLITRK1 because it was linked last
year to a related impulse-control disorder called Tourette syndrome, which
causes repetitive behaviors such as blinking, throat-clearing or shouting
obscenities.
The parent of one Tourette patient carried the SLITRK1 mutation but
displayed only symptoms of trichotillomania, not Tourette.
The Duke team further studied SLITRK1 and found two mutations in the SLITRK1
gene among some individuals with trichotillomania but not in their unaffected
family members. Mutations are changes in the structure of a gene that alter how
the gene behaves. The researchers estimate that the SLITRK1 mutations account
for 5 percent of trichotillomania cases.
The SLITRK1 gene is involved in forming connections among neurons, or brain
cells. The researchers hypothesize that the two mutations in SLITRK1 cause
neurons to develop faulty connections and that this faulty "wiring" produces the
urge to pull one's hair.
While SLITRK1 is the first gene linked with trichotillomania, numerous other
genes likely contribute to this disorder and other psychiatric conditions, said
senior study investigator Allison Ashley-Koch, Ph.D., assistant professor of
medical genetics and researcher in the Duke Center for Human Genetics.
"The SLITRK1 gene could be among many other genes that are likely interact with
each other and environmental factors to trigger trichotillomania and other
psychiatric conditions," Ashley-Koch said. "Such discoveries could open the door
for genetic testing, which is completely unheard of in the field of psychiatry."
Compared with neurological diseases, the identification of genes which underlie
psychiatric disorders have only just begun, she said. Few other examples exist
where a specific gene is known to trigger a psychiatric condition, although it
is generally accepted that genetic factors play an important role.
Psychiatric illnesses are widespread, affecting one in four Americans, according
to the National Institutes of Mental Health. They are the leading cause of
disability for Americans between the ages of 15 and 44. The most common
disorders are depression and anxiety disorders, such as panic disorder,
obsessive compulsive disorder and social phobia.
October 1-8, 2006, is National Trichotrillomania Awareness Week.