donderdag 8 oktober 2009

Genome-Wide Study of Autism

(Ha! they found the genes, yet again?!?!)

Published In Nature

Combining family- and population-based approaches sheds new light on the potential roles of both common and rare forms of human genetic variationIn one of the first studies of its kind, an international team of researchers has uncovered a single-letter change in the genetic code that is associated with autism.

The finding, published in the October 8 issue of the journal Nature, implicates a neuronal gene not previously tied to the disorder and more broadly, underscores a role for common DNA variation.

In addition, the new research highlights two other regions of the genome, which are likely to contain rare genetic differences that may also influence autism risk.

"These discoveries are an important step forward, but just one of many that are needed to fully dissect the complex genetics of this disorder, " said Mark Daly, one of the study's senior authors, a senior associate member at the Broad Institute of Harvard and MIT and an associate professor at the Center for Human Genetic Research at Massachusetts General Hospital (MGH).

"The genomic regions we've identified help shed additional light on the biology of autism and point to areas that should be prioritized for further study."

"The biggest challenge to finding the genes that contribute to autism is having a large and well studied group of patients and their family members, both for primary discovery of genes and to test and verify the discovery candidates," said Aravinda Chakravarti, professor of medicine, pediatrics and molecular biology and genetics at the McKusick-Nathans Institute of Genetic Medicine at Johns Hopkins, and one of the study's senior authors. "This latest finding would not have been possible without these many research groups and consortia pooling together their patient resources. Of course, they would not have been possible without the genomic scanning technologies either."

Autism is a common neurodevelopmental disorder characterized by impaired social, behavioral and communication abilities. (How long will they keep on repeating this stereotype of Autism like stupid parrots, only God knows!!!)

Compared to other complex diseases, which are caused by a complicated mix of genetic, environmental and other factors, autism is highly heritable - roughly 90% of the disorder is thought to be genetic in origin. (NO KIDDING!!! No mercury from vaccines causing it? No other stupid conclusions?)

Yet the majority of autism cases cannot be attributed to known inherited causes. (Yes, to known inherited causes, maybe you have a lot to still learn? Maybe you dear Science do not know ALL there is to know about inherited causes? How about that possibility? Huh?)

Modern approaches that harness genome-scale technologies have begun to yield some insights into autism and its genetic underpinnings. However, the relative importance of common genetic variants, which are generally present in the human population at a frequency of about 5%, as well as other forms of genetic variation, remains an unresolved question. (Exactly!)

To more deeply probe autism's complex genetic architecture, a large multinational collaboration led by researchers at the Broad Institute of Harvard and MIT, Massachusetts General Hospital, Johns Hopkins University and elsewhere devised a two-pronged, genome-scale approach.

The first component makes use of a family-based method (called "linkage") that analyzes DNA from autism patients and their family members to detect portions of the genome that harbor rare but high-impact DNA variants. The second harnesses a population-based method (known as "association" ) that examines DNA from unrelated individuals and can expose common genetic variants associated with autism and which tend to exert more modest effects.

"Given the genetic complexity of autism, it's unlikely that a single method or type of genomic variation is going to provide us with a complete picture," said Daly.
"Our approach of combining multiple complementary methods aims to meet this critical challenge."

For their initial studies, the researchers examined roughly half a million genetic markers in more than 1,000 families from the Autism Genetic Resource Exchange (AGRE) and the US National Institute of Mental Health (NIMH) repositories. Follow-up analyses were conducted in collaboration with the Autism Genome Project as well as other international groups.

"We are deeply grateful to all of the patients and their families who made this work possible," said Daly.The researchers' results highlight three regions of the human genome. These include parts of chromosomes 6 and 20, the top-scoring regions to emerge from the family-based linkage studies. Although further research is needed to localize the exact causal changes and genes within these regions that contribute to autism, these findings can help guide future work.

Read more:

donderdag 1 oktober 2009

Before Lucy came Ardi

New earliest hominid found

AP –Dr. C. Owen Lovejoy, Kent State University professor of anthropology, stands next to the reconstructed skeleton of "Lucy," a near-complete fossil of a human ancestor that walked upright more than three million years ago. A team of researchers including Lovejoy today unveiled research findings of a skeleton older than "Lucy," nicknamed "Ardi.

By RANDOLPH E. SCHMID, AP Science Writer Randolph E. Schmid, Ap Science Writer

WASHINGTON – The story of humankind is reaching back another million years as scientists learn more about "Ardi," a hominid who lived 4.4 million years ago in what is now Ethiopia. The 110-pound, 4-foot female roamed forests a million years before the famous Lucy, long studied as the earliest skeleton of a human ancestor.

This older skeleton reverses the common wisdom of human evolution, said anthropologist C. Owen Lovejoy of Kent State University.
Rather than humans evolving from an ancient chimp-like creature, the new find provides evidence that chimps and humans evolved from some long-ago common ancestor — but each evolved and changed separately along the way.

"This is not that common ancestor, but it's the closest we have ever been able to come," said Tim White, director of the Human Evolution Research Center at the University of California, Berkeley.
The lines that evolved into modern humans and living apes probably shared an ancestor 6 million to 7 million years ago, White said in a telephone interview.
But Ardi has many traits that do not appear in modern-day African apes, leading to the conclusion that the apes evolved extensively since we shared that last common ancestor.
A study of Ardi, under way since the first bones were discovered in 1994, indicates the species lived in the woodlands and could climb on all fours along tree branches, but the development of their arms and legs indicates they didn't spend much time in the trees. And they could walk upright, on two legs, when on the ground.

Formally dubbed Ardipithecus ramidus — which means root of the ground ape — the find is detailed in 11 research papers published Thursday by the journal Science.
"This is one of the most important discoveries for the study of human evolution," said David Pilbeam, curator of paleoanthropology at Harvard's Peabody Museum of Archaeology and Ethnology.

"It is relatively complete in that it preserves head, hands, feet and some critical parts in between. It represents a genus plausibly ancestral to Australopithecus — itself ancestral to our genus Homo," said Pilbeam, who was not part of the research teams.
Scientists assembled the skeleton from 125 pieces.
Lucy, also found in Africa, thrived a million years after Ardi and was of the more human-like genus Australopithecus.

"In Ardipithecus we have an unspecialized form that hasn't evolved very far in the direction of Australopithecus. So when you go from head to toe, you're seeing a mosaic creature that is neither chimpanzee, nor is it human. It is Ardipithecus," said White.

White noted that Charles Darwin, whose research in the 19th century paved the way for the science of evolution, was cautious about the last common ancestor between humans and apes.
"Darwin said we have to be really careful. The only way we're really going to know what this last common ancestor looked like is to go and find it. Well, at 4.4 million years ago we found something pretty close to it," White said. "And, just like Darwin appreciated, evolution of the ape lineages and the human lineage has been going on independently since the time those lines split, since that last common ancestor we shared."

Some details about Ardi in the collection of papers:

• Ardi was found in Ethiopia's Afar Rift, where many fossils of ancient plants and animals have been discovered. Findings near the skeleton indicate that at the time it was a wooded environment. Fossils of 29 species of birds and 20 species of small mammals were found at the site.

• Geologist Giday WoldeGabriel of Los Alamos National Laboratory was able to use volcanic layers above and below the fossil to date it to 4.4 million years ago.

• Ardi's upper canine teeth are more like the stubby ones of modern humans than the long, sharp, pointed ones of male chimpanzees and most other primates. An analysis of the tooth enamel suggests a diverse diet, including fruit and other woodland-based foods such as nuts and leaves.

• Paleoanthropologist Gen Suwa of the University of Tokyo reported that Ardi's face had a projecting muzzle, giving her an ape-like appearance. But it didn't thrust forward quite as much as the lower faces of modern African apes do. Some features of her skull, such as the ridge above the eye socket, are quite different from those of chimpanzees. The details of the bottom of the skull, where nerves and blood vessels enter the brain, indicate that Ardi's brain was positioned in a way similar to modern humans, possibly suggesting that the hominid brain may have been already poised to expand areas involving aspects of visual and spatial perception.

• Ardi's hand and wrist were a mix of primitive traits and a few new ones, but they don't include the hallmark traits of the modern tree-hanging, knuckle-walking chimps and gorillas. She had relatively short palms and fingers which were flexible, allowing her to support her body weight on her palms while moving along tree branches, but she had to be a careful climber because she lacked the anatomical features that allow modern-day African apes to swing, hang and easily move through the trees.

• The pelvis and hip show the gluteal muscles were positioned so she could walk upright.

• Her feet were rigid enough for walking but still had a grasping big toe for use in climbing.

The research was funded by the National Science Foundation, the Institute of Geophysics and Planetary Physics of the University of California, Los Alamos National Laboratory, the Japan Society for the Promotion of Science and others.
My comments:
Maybe one human kind evolved from the apes and the other from Ardi... Now who knows? Could it be that the Autistics and the Neurotypicals actually had different ancestors?
Wasn't it Temple Grandin who said that Autistics think like the animals? Well, maybe they evolved from the animals. Maybe that is because they are more in tune with the Earth, the nature, the cosmos...
Maybe we just different human species. Hey science, did you ever think of that???