Corporate Banner
Satellite Banner
Scientific Communities
Become a Member | Sign in
Home>News>This Article

Where Chromosomes Agree, Stanford researchers Trace Human History

Published: Monday, August 20, 2012
Last Updated: Monday, August 20, 2012
Bookmark and Share
Examining shared stretches of genome from dozens of world populations, Stanford biologists have found a new way, not only to find signatures of human migrations and marriage practices, but to help find hidden disease genes.

Your genome is a window onto your heritage – or, more precisely, several windows. There are the marks left by human evolution, the traces of ancient human migrations out of Africa and, scattered throughout, clues to your immediate ancestors' marriage habits.

This last detail is particularly interesting to medical geneticists. They're looking for the genes underlying rare, recessive diseases that mainly crop up in populations with a high number of marriages among close relatives, known as consanguineous marriages.

But this can be like looking for a needle in a haystack. Teasing out the stretches of genome that are shared among affected individuals due to a recent common ancestor, rather than from vestiges of deep population history, would significantly reduce the amount of hay.

A group of researchers, led by Stanford biology research associate Trevor Pemberton and biology Associate Professor Noah Rosenberg, has developed a way to attempt to do just that, laying bare worldwide genome patterns in the process.

The research paper, authored with Stanford biology Professor Marcus Feldman, Devin Absher and Richard Myers of the HudsonAlpha Institute for Biotechnology, and Jun Li of the University of Michigan, appeared Thursday in the American Journal of Human Genetics.

Chromosomal geography

Runs of homozygosity, or ROH, are segments of the genome where both chromosomes are identical. Homozygosity is what allows recessive traits, like blue eyes or cystic fibrosis, to appear at all – otherwise, the presence of a single dominant counterpart for a gene would mask the recessive characteristic.

Researchers have considered ROH before, but this comprehensive study of nearly 2,000 individuals from 64 populations across the world took a different approach. Using a new statistical model, the researchers "can disentangle ROH that are due to ancient population history from those that are due to recent consanguineous marriages," said Pemberton.

There are three flavors of ROH, separated by length. These all "follow different patterns," Pemberton explained, "which is what you'd expect when there are different processes underlying each of them."

Short- and middling-length ROH both vary with geography. Not only do they show distinct patterns on different continents, they increase in number as you move farther away from East Africa. It's a clear artifact of ancient waves of human migration.

"It's something novel, to see the signature of the distance from Africa in the ROH by separating them into classes of different size," Rosenberg said.

Africa, accordingly, also has the most diverse array of these short and intermediate ROH, while more recently populated regions such as Oceania and the Americas have the fewest.

These runs hearken back to events that are tens of thousands of years old. And many of the short runs – the more ancient of the two – appear to be fragments of even older ROH.

Gene hunting

The longest ROH, however, follow a different pattern. Younger and rarer, these runs don't obey a simple out-of-Africa progression. Instead, they appear most often in societies that have a history of marriage between relatives – in the Middle East and Central and South Asia, in particular. Adherence to the caste system in certain Indian towns, for instance, can severely limit spouse options.

These newer runs are also the ones that may help researchers narrow in on the chromosomal regions harboring the genes behind rare, recessive conditions –typically a side effect of relatively recent consanguineous marriage.

Researchers should be able to compare the ROH of an individual with a disease to those same chromosomal stretches in unaffected members of the same population group. "If it's frequently homozygous in the general population, you can largely discount the chromosomal region as a candidate," said Pemberton. "If it's rarely homozygous in the general population, it becomes a stronger candidate."

The group has already begun tentative collaborations with medical geneticists and has released a genomic map of the ROH locations.

"The idea is, the resource will be there and available for anyone who wants to come in and answer a question," Rosenberg said.

Further Information
Access to this exclusive content is for Technology Networks Premium members only.

Join Technology Networks Premium for free access to:

  • Exclusive articles
  • Presentations from international conferences
  • Over 2,800+ scientific posters on ePosters
  • More Than 4,000+ scientific videos on LabTube
  • 35 community eNewsletters

Sign In

Forgotten your details? Click Here
If you are not a member you can join here

*Please note: By logging into you agree to accept the use of cookies. To find out more about the cookies we use and how to delete them, see our privacy policy.

Related Content

New Class of RNA Tumor Suppressors Identified
Two short, “housekeeping” RNA molecules block cancer growth by binding to an important cancer-associated protein called KRAS. More than a quarter of all human cancers are missing these RNAs.
Thursday, November 26, 2015
Ancient Viral Molecules Essential for Human Development
Genetic material from ancient viral infections is critical to human development, according to researchers at the Stanford University School of Medicine.
Wednesday, November 25, 2015
Sleep Deprivation Affects Stem Cells, Reducing Transplant Efficiency
Although the research was done in mice, the findings have possible implications for bone marrow transplants, more properly called hematopoietic stem cell transplants, in humans.
Friday, October 16, 2015
Enzyme Malfunction May be Why Binge Drinking Can Lead to Alcoholism
A new study in mice shows that restoring the synthesis of a key brain chemical tied to inhibiting addictive behavior may help prevent alcohol cravings following binge drinking.
Friday, October 09, 2015
How Cell Growth Triggers Cell Division
Researchers in Jan Skotheim's lab have discovered a previously unknown mechanism that controls how large cells grow, an insight that could one day provide insight into attacking diseases such as cancer.
Wednesday, October 07, 2015
Tension Helps Heart Cells Develop Normally in the Lab
Stanford engineers have uncovered the important role tension plays in growing heart cells out of the body.
Monday, October 05, 2015
Drug Disarms Deadly C. difficile Bacteria Without Destroying Healthy Gut Flora
A drug that blocks the intestinal pathogen without killing resident, beneficial microbes may prove superior to antibiotics, currently the front-line treatment for the infection.
Friday, September 25, 2015
Virus Re-Engineered to Deliver Targeted Therapies
Researchers stripped a virus of its infectious machinery and turned its benign core into a delivery vehicle that can target sick cells while leaving healthy tissue alone.
Thursday, September 24, 2015
Combination Drug Therapy Shrinks Pancreatic Tumors In Mice
Two drugs that affect the structure and function of DNA have been found to block the growth of pancreatic tumor cells in mice, researchers hope the drugs can soon be tested in humans with the disease.
Thursday, September 24, 2015
Delivering Missing Protein Heals Damaged Hearts in Animals
Researchers have discovered that a particular protein, Fstl1, plays a key role in regenerating dead heart-muscle cells.
Tuesday, September 22, 2015
Key Mechanism in Gene Expression Discovered
RNA polymerase II makes life possible by expressing genes. Now, a team of Stanford biologists, chemists and applied physicists has observed it at work in real time.
Thursday, September 17, 2015
Drug Prevents Type 1 Diabetes In Mice
A compound that blocks the synthesis of hyaluronan, a substance generally found in in all body tissue, protected mice from getting Type 1 diabetes. The compound is already approved in Europe and Asia for the treatment of gallbladder disease.
Wednesday, September 16, 2015
New Method for Producing Vital Cancer Drug
Stanford scientists produced a common cancer drug – previously only available from an endangered plant – in a common laboratory plant.
Tuesday, September 15, 2015
Scientists Home In On Origin Of Human, Chimpanzee Facial Differences
A study of species-specific regulation of gene expression in chimps and humans has identified regions important in human facial development and variation.
Monday, September 14, 2015
X-ray Laser Experiment Could Help in Designing Drugs for Brain Disorders
Scientists found that when two protein structures in the brain join up, they act as an amplifier for a slight increase in calcium concentration, triggering a gunshot-like release of neurotransmitters from one neuron to another.
Monday, August 24, 2015
Scientific News
High Throughput Mass Spectrometry-Based Screening Assay Trends
Dr John Comley provides an insight into HT MS-based screening with a focus on future user requirements and preferences.
How a Genetic Locus Protects Adult Blood-Forming Stem Cells
Mammalian imprinted Gtl2 protects adult hematopoietic stem cells by restricting metabolic activity in the cells' mitochondria.
Genetic Basis of Fatal Flu Side Effect Discovered
A group of people with fatal H1N1 flu died after their viral infections triggered a deadly hyperinflammatory disorder in susceptible individuals with gene mutations linked to the overactive immune response, according to a recent study.
New Tech Vastly Improves CRISPR/Cas9 Accuracy
A new CRISPR/Cas9 technology developed by scientists at UMass Medical School is precise enough to surgically edit DNA at nearly any genomic location, while avoiding potentially harmful off-target changes typically seen in standard CRISPR gene editing techniques.
The MaxSignal Colistin ELISA Test Kit from Bioo Scientific
Kit can help prevent the antibiotic apocalypse by keeping last resort drugs out of the food supply.
"Good" Mozzie Virus Might Hold Key to Fighting Human Disease
Australian scientists have discovered a new virus carried by one of the country’s most common pest mosquitoes.
Non-Disease Proteins Kill Brain Cells
Scientists at the forefront of cutting-edge research into neurodegenerative diseases such as Alzheimer’s and Parkinson’s have shown that the mere presence of protein aggregates may be as important as their form and identity in inducing cell death in brain tissue.
Closing the Loop on an HIV Escape Mechanism
Research team finds that protein motions regulate virus infectivity.
New Class of RNA Tumor Suppressors Identified
Two short, “housekeeping” RNA molecules block cancer growth by binding to an important cancer-associated protein called KRAS. More than a quarter of all human cancers are missing these RNAs.
Potential Treatment for Life-Threatening Viral Infections Revealed
The findings point to new therapies for Dengue, West Nile and Ebola.
Scroll Up
Scroll Down
Skyscraper Banner

Skyscraper Banner
Go to LabTube
Go to eposters
Access to the latest scientific news
Exclusive articles
Upload and share your posters on ePosters
Latest presentations and webinars
View a library of 1,800+ scientific and medical posters
2,800+ scientific and medical posters
A library of 2,500+ scientific videos on LabTube
4,000+ scientific videos