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Going from wolf
to Weimaraner

By Tina Hesman Saey

The largest-ever genetic family tree of dogs and wolves traces dogs’ origin to the Middle East, an international group of researchers reports online March 17 in Nature. The finding fits with archaeological evidence that dogs were domesticated in the Middle East or Eastern Europe, and contradicts earlier genetic data suggesting that man’s best friend originated in China.

New research suggests dogs emerged
from wolf populations in the Middle
East or Eastern Europe, not East Asia.

“Nothing ever seals the deal, but this is pretty strong evidence for dog domestication in the Near East cultural region,” says Carlos Driscoll, a geneticist at the National Cancer Institute at Frederick, Md., who was not involved in the research.

In the new study, scientists analyzed 48,000 DNA markers, called SNPs, scattered across the genomes of 85 dog breeds as well as gray wolves from 11 different populations around the world. SNPs, or single nucleotide polymorphisms, are letters in the genetic instruction book that can vary between individuals. In terms of SNPs, East Asian dog breeds are not more genetically diverse than other breeds, the team found.

Modern dog breeds, those that first appeared in the Victorian era, have more genetic kinship with Middle Eastern wolves than with other wolf populations, indicating that dogs probably stem from wolf forebears in that part of the world.

Family genomics makes its debut
Full dna studies of parents and children pinpoint mutations

By Laura Sanders

Genome sequencing has become a family affair. For the first time, two independent teams of researchers have identified genetic changes underlying rare diseases by comparing complete DNA sequences from patients with similar data from their immediate relatives.

The studies, appearing online March 10 in the New England Journal of Medicine and Science, show how powerful family genome sequencing can be for understanding inherited conditions, and how the falling costs of such analyses promise to revolutionize the study, diagnosis and treatment of disease.

“It’s great to see rare disease genes
being identified by sequence-based
approaches,” says geneticist Stacey
Gabriel of the Broad Institute, a joint
research center of MIT and Harvard
University. In these early days of using
gene sequencing as a discovery tool, she
says, “family-based studies are a really
interesting place to start.”
The authors of the paper in Science
sequenced the complete genomes of
two parents, a son and a daughter. Both
children had a pair of rare genetic dis-
eases — Miller syndrome, characterized
by craniofacial abnormalities, and
primary ciliary dyskinesia, which affects
the respiratory tract. By comparing the
parents’ genomes with the children’s,
researchers were able to pinpoint two
likely genetic culprits. Knowing exactly
which genetic changes trigger a disease
could help researchers tailor treatments,
for example by prescribing drugs that
work on the relevant disease pathway or
providing genetic counseling to families.

event, he says. He and his colleagues then compared select regions of his DNA with that of his parents and seven siblings, three of whom also have Charcot-Marie-Tooth disease.

This targeted approach pinpointed
two mutations in a gene called SH3TC2
as the cause of Lupski’s form of the dis-
ease. “We’ve worked on studying this
disease close to 25 years,” he says. “ We’ve
never been able to identify the cause of
my specific disease in my family. We now
know the exact thing going on.”
The cost of sequencing has dropped
dramatically since the days of the
Human Genome Project, which spent
an estimated $2.7 billion to produce
a single human genome. Sequencing
Lupski’s complete genome cost around
$50,000, and he estimates that in the
six months since his team’s study was
conducted, the cost has dropped to
about half that amount.