Scripps Research Institute scientists have taken a step closer
to understanding the cause of Friedreich's ataxia, a
debilitating neurological condition that affects tens of
thousands of people worldwide, and so far has no cure.
Researchers already know that the disease arises from the
silencing of the gene FXN, due to an abnormally expanded stretch
of DNA within the gene. The length of this 'triplet repeat
expansion' determines the degree of gene silencing, and thus the
severity of the disease. This length also tends to change from
carrier parents to patient offspring. But the cause of this
genetic instability hasn't been clear. After creating a stem
cell model of the disease from patients' skin cells, the Scripps
Research scientists found strong evidence for the involvement of
a DNA repair enzyme in the FXN triplet repeat expansion. The
finding suggests that the expansion is driven by the enzyme's
misguided attempts to repair what it recognises as DNA damage.
'We've known that in other triplet repeat expansi