Scientists identify gene linked to facial, skull and cognitive impairment

July 5, 2012
A gene whose mutation results in malformed faces and skulls as well as mental retardation has been found by scientists. Credit: Phil Jones

A gene whose mutation results in malformed faces and skulls as well as mental retardation has been found by scientists.

They looked at patients with Potocki-Shaffer syndrome, a rare disorder that can result in significant abnormalities such as a small head and chin and , and found the gene PHF21A was mutated, said Dr. Hyung-Goo Kim, molecular geneticist at the Medical College of Georgia at Georgia Health Sciences University.

The scientists confirmed PHF21A's role by suppressing it in , which developed head and similar to those in patients. "With less PHF21A, brain cells died, so this gene must play a big role in neuron survival," said Kim, lead and corresponding author of the study published in The . They reconfirmed the role by giving the gene back to the malformed – studied for their adeptness at regeneration – which then became essentially normal. They also documented the gene's presence in the craniofacial area of normal mice.

While giving the normal gene unfortunately can't cure patients as it does zebrafish, the scientists believe the finding will eventually enable genetic screening and possibly early intervention during fetal development, including therapy to increase PHF21A levels, Kim said. It also provides a compass for learning more about face, skull and brain formation.

The scientists zeroed in on the gene by using a distinctive chromosomal break found in patients with Potocki-Shaffer syndrome as a starting point. Chromosomes – packages of DNA and protein – aren't supposed to break, and when they do, it can damage in the vicinity.

"We call this breakpoint mapping and the breakpoint is where the trouble is," said Dr. Lawrence C. Layman, study co-author and Chief of the MCG Section of Reproductive Endocrinology, Infertility and Genetics. Damaged genes may no longer function optimally; in PHF21A's case it's about half the norm.

"When you see the chromosome translocation, you don't know which gene is disrupted," Layman said. "You use the break as a focus then use a bunch of molecular techniques to zoom in on the gene." Causes of chromosomal breaks are essentially unknown but likely are environmental and/or genetic, Kim said.

Little was known about PHF21A other than its role in determining how tightly DNA is wound in a package with proteins called histones. How tightly DNA is wound determines whether proteins called transcription factors have the access needed to regulate gene expression, which is important, for example, when a gene needs to be expressed only at a specific time or tissue. PHF21A is believed to primarily work by suppressing other genes, for example, ensuring that genes that should be expressed only in don't show up in other cell types, Kim said.

Next steps include using PHF21A as a sort of geographic positioning system to identify other "depressor" genes it regulates then screening patients to look for mutations in those genes as well. "We want to find other people with different genes causing the same problem," Layman said, and they suspect the genes PHF21A interacts with or regulates are the most likely suspects. It's too early to know what percentage of Potocki-Shaffer syndrome patients have the PHF21A mutation, Kim noted. "Now that we know the causative gene, we can sequence the gene in more patients and see if they have a mutation," Layman said.

They also want to look at less-severe forms of mental deficiency, including autism, for potentially milder of PHF21A. More than a dozen of the 25,000 human genes are known to cause craniofacial defects and , which often occur together, Kim said.

Explore further: Evolved, mutated gene module linked to Joubert syndrome

Related Stories

Evolved, mutated gene module linked to Joubert syndrome

January 26, 2012
A team led by researchers at the University of California, San Diego School of Medicine reports that newly discovered mutations in an evolved assembly of genes cause Joubert syndrome, a form of syndromic autism.

Rare muscular dystrophy gene mutations discovered

April 24, 2012
(Medical Xpress) -- Research co-led by Radboud University Nijmegen Medical Centre and the Wellcome Trust Sanger Institute has revealed gene mutations that account for 15 per cent of all babies born with Walker-Warburg syndrome, ...

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.