Trichothiodystrophy
gene mutation causes fever-related hair loss
In some patients with a rare genetic disorder called trichothiodystrophy
(TTD), a simple fever can cause them to lose all of their hair.
The hair grows back after the fever has passed, but now researchers
think they know the reason why the patients lose their hair in the
first place. Patients with this disorder, already have brittle hair,
nails and scaly skin. But some patients with the disorder have an
additional burden: during a fever, they can lose their hair in 1
or
2 days.
Dr. Jan H. J. Hoeijmakers from Erasmus University in the Netherlands
and colleagues looked at four patients who had TTD and fever-related
hair loss. The investigators analyzed the patients' cells and found
that high temperatures impaired the cells' ability to repair damaged
DNA, as well as to translate genes into proteins. All four patients
had a particular mutation in the gene that causes TTD.
The researchers were particularly interested in this mutation because
it is "temperature-sensitive," meaning that it only is
activated under conditions of increased heat, such as that produced
by fever. Previously, scientists have mostly seen these types of
defects in lower organisms such as bacteria and yeast--they have
not been fully identified in humans.
Writing in the March issue of Nature Genetics, Hoeijmakers and
colleagues speculate that during fever the same defect that causes
the hair to be naturally brittle in these patients is aggravated
even further and introduces a "highly fragile point at the
base of the hair resulting in
immediate complete hair loss."
Patients with TTD also suffer from features of premature aging
and the researchers have developed a mouse that has the same genetic
defects and symptoms as humans with TTD. They hope that their research
on TTD may shed light on the normal aging process in humans. The
authors believe that these patients age prematurely due to a problem
with the same malfunctioning protein that causes brittle hair. "We
have recently discovered that a number of the symptoms are associated
with accelerated aging, so we hope to obtain insight into the mechanism
that underlies aspects of natural aging and age-related disease,"
Hoeijmakers said.
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