----- Original Message -----
From: Ali
To: Undisclosed-Recipient:;
Sent: Saturday, March 14, 2009 12:31 PM
Subject: [VV] Discovery of new gene that causes Leber congenital amaurosisand
retinitis pigmentosa
Published: Thursday, 5-Mar-2009
Medical Research News
The team of Dr. Robert Koenekoop which includes Dr. Irma Lopez from the
Research Institute of the
MUHC at the Montreal Children's Hospital played a crucial role in the
international collaboration
that led to the discovery of a new gene that causes Leber congenital amaurosis
(LCA) and retinitis
pigmentosa (RP), two devastating forms of childhood blindness.
This finding of this new gene, called SPATA7, is remarkable because it
identifies a new retinal
metabolic disease pathway that may be crucial for many patients. It also opens
a new avenue for a
potential genetic therapy. Gene therapy targeting different genes has recently
proved successful for
the same disease in human subjects. The study will be published on March 5th,
2009 in the American
Journal of Human Genetics .
New cell mechanism at play
Researchers have now identified a total of fifteen genes involved in LCA, but
SPATA7 is the first
gene with a mutation that disrupts the protein transport between two important
compartments of the
cell: the endoplasmic reticulum and the Golgi apparatus. All proteins in every
cell have to pass
through this transport pathway; thus SPATA7 plays a major role and its mutation
may affect many
aspects of vision.
"Until now we were not aware that this cellular mechanism played a role in LCA
or any other eye
disease. This is a very important step that opens up a number of new research
avenues, particularly
in our understanding of the specific cellular processes involved in blindness.
This finding also
increases the number of potential therapeutic targets and therefore the chances
of finding a
treatment. We are extremely motivated by all of these new possibilities,"
explained Dr. Koenekoop.
First step towards gene therapy
"This is an incredible discovery that gives great hope to LCA patients and
their families, that gene
based therapies can and will be developed to restore sight," said Sharon Colle,
President and CEO of
The Foundation Fighting Blindness, the leading private charity for vision
research. "We are proud to
fund such important discoveries involving prominent Canadian researchers and
institutions."
A careful assessment of patients with some specific genetic types of LCA also
demonstrated that
their retinal cells (specifically the rod and cone photoreceptors), although
not functional for
vision, were still present and in relatively good condition. This critical
observation will allow
researchers to continue on the path towards gene therapies. Therapies targeting
different genes for
the same disease have already shown success in the United Kingdom and in the
US, meaning that LCA
patients can now enjoy hope for the future.
A new and innovative technology
SPATA7 was identified using an innovative technology developed in the different
laboratories
involved in this international collaboration. "We started this protocol about
two years ago, and it
has already helped us to identify four new genes associated with LCA and RP
before we discovered
SPATA7," explained Dr Koenekoop.
The technique is based on DNA-chips and involves three steps: first the genetic
material of the
patient is screened to find mutations in 14 specific LCA and RP genes. The LCA
and RP patients that
are negative for this detailed screen are then subjected to a second DNA chip,
this one to identify
significant stretches of homozygosity in SNP markers. SNPs are single
nucleotide repeats, which are
natural variations in the human genome. These homozygous regions may contain
new genes and are
carefully probed based on functional information and then subjected to
sequencing. "This method is
indeed both very powerful and very promising for the future," said Dr.
Koenekoop.
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