Posts tagged intellectual disabilities
Articles and news from the latest research reports.
Fragile X Protein Linked to Nearly 100 Genes Involved in Autism
Doctors have known for many years that patients with fragile X syndrome, the most common form of inherited intellectual disability, are often also diagnosed with autism. But little has been known about how the two diagnoses are related.
Now a collaborative research effort at Duke University Medical Center and Rockefeller University has pinpointed the precise genetic footprint that links the two. The findings, published online in the journal Nature on Dec. 12, 2012, point the way toward new genetic testing that could more precisely diagnose and categorize the spectrum of autism-related disorders.
Fragile X syndrome is the most well understood single-gene cause of autism. It results from defects on a small part of the genetic code for a protein that researchers have dubbed the fragile X mental retardation protein, or FMRP.
Normally, FMRP plays an important role controlling production of other proteins in the brain and other organs. It does this by looking for specific genetic patterns located on the messages encoding proteins. When it locates these genetic flags, it attaches to them and, along with other signals, controls where and when protein is made.
In fragile X syndrome, this process breaks down because a defect in the gene causes the body to produce too little, or in some cases, none of the FMRP protein. As a result, additional proteins it would normally regulate are made in the wrong place and at the wrong time. Until now, little was known about how this process worked in people with the autism.
Using a combination of laboratory experiments and advanced bioinformatics, the research team, led by Thomas Tuschl, PhD, a Howard Hughes Medical Institute investigator at Rockefeller University, and Uwe Ohler, PhD, an associate professor in Biostatistics and Bioinformatics at the Duke Institute for Genome Sciences & Policy, identified both the genetic flags that FMRP is looking for and the genes it targets.
(Image courtesy of www.sueblimely.com)
Protein regulation linked to intellectual disability
Genetics researchers at the University of Adelaide have solved a 40-year mystery for a family beset by a rare intellectual disability - and they’ve discovered something new about the causes of intellectual disability in the process.
While many intellectual disabilities are caused directly by a genetic mutation in the so-called “protein coding” part of our genes, the researchers found that in their case the answer laid outside the gene and in the regulation of proteins.
Protein regulation involves the switching on or off of a protein by specific genes. As a consequence in this case, either too much or too little of this protein can trigger the disability.
The team has studied a large (anonymous) Australian family of 100 people, who for generations have not known the source of their genetically inherited condition.
The disability - which results in a lower IQ, behavioural problems such as aggression, and memory loss, and is linked with developmental delays, epilepsy, schizophrenia and other problems - affects only the male family members and can be passed on by the female family members to their children.
Genetic samples taken from the family and laboratory testing involving mice have confirmed that the protein produced by the HCFC1 (host cell factor C1) gene is the cause of this disability.
"The causes of intellectual disability generally are highly variable and the genetic causes in particular are numerous. The vast majority of intellectual disabilities are due to genetic mutations in proteins, so it was rather unexpected that we found this particular disability to be due to a regulatory mutation," says the leader of the study, Professor Jozef Gecz from the University of Adelaide’s School of Paediatrics and Reproductive Health.
"We’ve been researching this specific disability for 10 years and it’s taken us the last three years to convince ourselves that the protein regulation is the key," he says.
"For the family, this means we now have a genetic test that will determine whether or not a female member of the family is a carrier, which brings various benefits for the family.
"From a scientific point of view, this widens our viewpoint on the causes of these disabilities and tells us where we should also look for answers for those families and individuals without answers.
"This is just the tip of the iceberg in understanding the impact of altered gene regulation on intellectual disability - the gene regulatory landscape is much bigger than the protein coding landscape. We have already found, and I would expect to continue finding, a number of other intellectual disabilities linked with protein regulation over the next 20 years or so."
Professor Gecz and his team have published their findings in this month’s issue of the American Journal of Human Genetics.
(Source: adelaide.edu.au)