Autism Links On Chromosome 7 Revised DNA sequence homes in on break points.

More on this discovery. By Hannah Hoag.

A revamp of chromosome 7’s DNA sequence has brought to light genes associated with autism, several leukaemias and lymphomas1.

Geneticist Stephen Scherer, of the University of Toronto, and his colleagues identified the site of more than 100 new mutations linked to genetic disorders after studying the genetic makeup of more than 300 new patients and reviewing 1,570 published studies.

Doctors will be able to log onto a new dynamic database in which the
sequence anomalies are held, and determine whether a patient’s genetic
make-up matches those of others. As information is added to the
free-access database, more mutations may stand out. “It’s a quick way to identify
candidate genes for a disorder,” Scherer says.

Some of the mutations seen in patients with autism have turned up in
genes related to speech and communication, others are close to genes that
enable neurons to communicate.

The genetics of autism is complex, warns Beth Rosen-Sheidley of the
Tufts-New England Medical Center in Boston. “A single gene change doesn’t
seem to be sufficient in most families.” Any test for the disease would be
difficult to interpret, she says. “It’s a bit of a quagmire. One marker
for the disease might increase the risk, but by how much?”

To produce a precise map, Scherer’s team started with the draft
chromosome 7 sequence published by the private company Celera Genomics2.
They then filled in many of the gaps with data from the international
public consortium3.

The researchers admit that the resulting sequence is not completely
finished, but reckon that it is in good shape. Others feel, however, that
it has some way to go.

References Scherer, S. W. et al. Human Chromosome 7: DNA Sequence and
Biology. Science, published online, doi:10.1126/science.1083423 (2003).
|Article| Venter, C. J. et al. The Sequence of the Human Genome. Science,
291, 1304 – 1351, (2001). |Homepage| McPherson, J. D. et al. A physical
mapof the human genome. Nature, 409, 934 – 941, (2001). |Article|

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