Research discovers chromosome therapy to correct a severe chromosome defect

January 13, 2014

Geneticists from Ohio, California and Japan joined forces in a quest to correct a faulty chromosome through cellular reprogramming. Their study, published online today in Nature, used stem cells to correct a defective "ring chromosome" with a normal chromosome. Such therapy has the promise to correct chromosome abnormalities that give rise to birth defects, mental disabilities and growth limitations.

"In the future, it may be possible to use this approach to take cells from a patient that has a defective chromosome with multiple missing or duplicated genes and rescue those cells by removing the defective chromosome and replacing it with a normal chromosome," said senior author Anthony Wynshaw-Boris, MD, PhD, James H. Jewell MD '34 Professor of Genetics and chair of Case Western Reserve School of Medicine Department of Genetics and Genome Sciences and University Hospitals Case Medical Center.

Wynshaw-Boris led this research while a professor in pediatrics, the Institute for Human Genetics and the Eli and Edythe Broad Center of Regeneration Medicine and Stem Cell Research at UC, San Francisco (UCSF) before joining the faculty at Case Western Reserve in June 2013.

Individuals with ring chromosomes may display a variety of birth defects, but nearly all persons with ring chromosomes at least display short stature due to problems with cell division. A normal chromosome is linear, with its ends protected, but with ring chromosomes, the two ends of the chromosome fuse together, forming a circle. This fusion can be associated with large terminal deletions, a process where portions of the chromosome or DNA sequences are missing. These deletions can result in disabling genetic disorders if the genes in the deletion are necessary for normal cellular functions.

The prospect for effective counter measures has evaded scientists—until now. The international research team discovered the potential for substituting the malfunctioning ring chromosome with an appropriately functioning one during reprogramming of patient cells into induced pluripotent stem cells (iPSCs). iPSC reprogramming is a technique that was developed by Shinya Yamanaka, MD, PhD, a co-corresponding author on the Nature paper. Yamanaka is a senior investigator at the UCSF-affiliated Gladstone Institutes, a professor of anatomy at UCSF, and the director of the Center for iPS Cell Research and Application (CiRA) at the Institute for Integrated Cell-Material Sciences (iCeMS) in Kyoto University. He won the Nobel Prize in Medicine in 2012 for developing the reprogramming technique.

Marina Bershteyn, PhD, a postdoctoral fellow in the Wynshaw-Boris lab at UCSF, along with Yohei Hayashi, PhD, a postdoctoral fellow in the Yamanaka lab at the Gladstone Institutes, reprogrammed skin cells from three patients with abnormal brain development due to a rare disorder called Miller Dieker Syndrome, which results from large terminal deletions in one arm of chromosome 17. One patient had a ring chromosome 17 with the deletion and the other two patients had large terminal deletions in one of their chromosome 17, but not a ring. Additionally, each of these patients had one normal chromosome 17.

The researchers observed that, after reprogramming, the ring chromosome 17 that had the deletion vanished entirely and was replaced by a duplicated copy of the normal chromosome 17. However, the terminal deletions in the other two patients remained after reprogramming. To make sure this phenomenon was not unique to ring chromosome 17, they reprogrammed cells from two different patients that each had ring chromosomes 13. These reprogrammed cells also lost the ring chromosome, and contained a duplicated copy of the normal chromosome 13.

"It appears that ring chromosomes are lost during rapid and continuous cell divisions during reprogramming," said Yamanaka. "The duplication of the normal chromosome then corrects for that lost chromosome."

"Ring loss and duplication of whole chromosomes occur with a certain frequency in stem cells," explained Bershteyn. "When chromosome duplication compensates for the loss of the corresponding ring chromosome with a deletion, this provides a possible avenue to correct large-scale problems in a chromosome that have no chance of being corrected by any other means."

"It is likely that our findings apply to other ring chromosomes, since the loss of the ring chromosome occurred in cells reprogrammed from three different patients," said Hayashi.

"In theory, the way you could potentially correct a chromosome with deletions or duplications is to make a ring out of it and then get rid of the ring chromosome during reprogramming," added Wynshaw-Boris. "Ring are quite rare, but are much more common and cause a variety of severe birth defects. So far, it is only possible to do this chromosome therapy for in culture, not in human beings. However, it may be useful to use this for tissue repair of and other abnormalities found in individuals with chromosomal abnormalities as techniques for regenerative medicine are developed in the future."

Explore further: Keeping it together: 'Cord-stopper' protein complex makes chromosomes easier to move

More information: Cell-autonomous correction of ring chromosomes in human induced pluripotent stem cells, DOI: 10.1038/nature12923

Related Stories

Keeping it together: 'Cord-stopper' protein complex makes chromosomes easier to move

July 18, 2011
German scientists at EMBL Heidelberg have discovered how condensin keeps chromosome arms folded and easy-to-transport during cell division, potentially acting as a cord-stopper.

Researchers identify traffic cop mechanism for meiosis

December 12, 2013
Researchers at NYU and the Whitehead Institute for Biomedical Research have identified the mechanism that plays "traffic cop" in meiosis—the process of cell division required in reproduction. Their findings, which appear ...

Chromosome number changes in yeast

July 21, 2011
Researchers from Trinity College Dublin have uncovered the evolutionary mechanisms that have caused increases or decreases in the numbers of chromosomes in a group of yeast species during the last 100-150 million years. The ...

Mutations in cancer often affect the X chromosome

October 18, 2013
Every case of cancer originates from changes in a person's genetic material (mutations). These usually occur as "somatic mutations" in individual cells during an individual's lifetime, rather than being inherited from a person's ...

Recommended for you

Scientists provide insight into genetic basis of neuropsychiatric disorders

July 21, 2017
A study by scientists at the Children's Medical Center Research Institute at UT Southwestern (CRI) is providing insight into the genetic basis of neuropsychiatric disorders. In this research, the first mouse model of a mutation ...

Scientists identify new way cells turn off genes

July 19, 2017
Cells have more than one trick up their sleeve for controlling certain genes that regulate fetal growth and development.

South Asian genomes could be boon for disease research, scientists say

July 18, 2017
The Indian subcontinent's massive population is nearing 1.5 billion according to recent accounts. But that population is far from monolithic; it's made up of nearly 5,000 well-defined sub-groups, making the region one of ...

Mutant yeast reveals details of the aberrant genomic machinery of children's high-grade gliomas

July 18, 2017
St. Jude Children's Research Hospital biologists have used engineered yeast cells to discover how a mutation that is frequently found in pediatric brain tumor high-grade glioma triggers a cascade of genomic malfunctions.

Late-breaking mutations may play an important role in autism

July 17, 2017
A study of nearly 6,000 families, combining three genetic sequencing technologies, finds that mutations that occur after conception play an important role in autism. A team led by investigators at Boston Children's Hospital ...

Newly identified genetic marker may help detect high-risk flu patients

July 17, 2017
Researchers have discovered an inherited genetic variation that may help identify patients at elevated risk for severe, potentially fatal influenza infections. The scientists have also linked the gene variant to a mechanism ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.