THREE children suffering from Hurler鈥檚 syndrome, a rare inherited disease
that would normally kill them before they reached 10 years old, this week began
a pioneering course of gene therapy designed to remedy their defective gene.
Children with Hurler鈥檚 syndrome lack a 鈥渉ousekeeping鈥� enzyme that clears out
the molecular rubbish in cells. As the debris accumulates, the symptoms grow
worse, resulting in visible deformities and mental retardation.
In the first trial of its kind, Mike Dexter and his colleagues at the
Christie Hospital in Manchester aim to equip the children with the gene they
need to make the missing enzyme, alpha-L-iduronidase. The enzyme breaks down
mucopolysaccharides, which build up in cells as connective tissue wears out.
Dexter鈥檚 team will insert good copies of the gene into bone marrow cells
extracted from the patients.
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The aim is to get the gene into stem cells鈥攑rimitive, undifferentiated
cells which mature into white blood cells. The team hopes that as the white
cells circulate, the alpha-L-iduronidase they secrete will diffuse into cells
that are unable to make it. 鈥淧otentially, the remedy would be permanent because
stem cells persist throughout adult life and undergo self-renewal,鈥� says
Dexter.
All the patients are under 18 months old to maximise the chance of success.
鈥淚t鈥檚 important to start the treatment before patients have any physical signs
of disease, because you can鈥檛 reverse it,鈥� says Dexter.