As written by Parent Advocates, Liz Marfia-Ash and Phil Ash with contributions from Dr. Stephen Traynelis, Dr. Tim Benke and Melissa Gibbons (Genetic Counselor).
What is a GRIN2B Mutation?
GRIN2B is not the name of a disease or disorder, but is the name of a gene located on the 12th chromosome. Its function is to encode a protein that forms a receptor responsible for sending chemical messages to the brain. A mutation on the GRIN2B gene means that some portion of this specific genetic code either got deleted, duplicated or rearranged.
What causes GRIN2B?
A GRIN2B mutation occurs randomly and spontaneously at or shortly after conception. The reasons for these genetic changes are unknown. It is possible for a parent to be a carrier of the mutation and pass it on to their children, but most known cases are found to be de novo (meaning, it occurs spontaneously in the DNA of the egg or sperm that formed the new child).
Who can get a GRIN2B Mutation?
Males and females of all races can be born with a GRIN2B variation. So far, approximately 84 individuals come from many different countries all over the world, including Australia, Canada, England, Italy, China, Sweden, Denmark, Norway, the Netherlands*, and the United States.
* When the GRIN2B Facebook group was first formed, many of the original members were from the Netherlands. These individuals were some of the few who participated in a survey to gather content for this website. This is why you will see mention of several Dutch websites and Resources throughout this site.
I’m confused by the terms. What is the difference between a variation and a mutation?
Anytime a change is made to a gene, it can be referred to as a change, variation, mutation or sometimes chromosomal rearrangement. These terms are all often used interchangeably.
What are the Symptoms?
Symptoms can vary from person to person depending on the type and location of the mutation, but the most common traits (as reported by parents in the GRIN2B parent support group) are hypotonia (low muscle tone), global developmental delay, some form of intellectual disability and non-verbal or delayed speech. For a detailed list of additional symptoms, please check out our Symptoms infographic on About GRIN2B.
Is there a cure?
At this time, there is no cure for a GRIN2B change because it occurs at the genetic level of an individual. However, doctors are planning some potentially promising clinical trials for medication that may reduce associated symptoms. We will update our News page as soon as we know details about possible clinical trials.
What are the treatments?
While there is no cure for a GRIN2B change, physical, occupational, and speech therapies can help manage symptoms in children and also help them reach developmental milestones. Epilepsy, if present, is treated by a specialist. There are no known medications on the market to specifically alleviate the symptoms associated with GRIN2B. However, there are a number of experimental medicines and homeopathic treatments that have been shown to have some success as reported by some parents in the GRIN2B parent support group. For more information, check out our Treatments page.
How is a GRIN2B mutation diagnosed?
GRIN2B changes are not diagnosed easily. Often GRIN2B children will have normal MRIs, normal EEGs, and normal chromosome pairings – common tests that can often help diagnose other, more common genetic disorders. In most instances, GRIN2B mutations are discovered through a genetic blood test called Whole Exome Sequencing (WES). This blood test examines the individual’s entire genetic makeup. This is compared with the genetic sequences of the parents. Through this test, rare genetic outliers like GRIN2B changes can be determined and diagnosed. It is important to note that this test has only really become more widely available and covered by insurance in the past few years, which explains why there are so few known individuals. As this test becomes more prevalent, we expect the number of individuals diagnosed with a GRIN2B change to grow.
What is the prognosis?
To date, we do not know of any deaths that have occurred in individuals due to complications with GRIN2B changes. Also, this disorder does not appear to be progressive, meaning it does not worsen over time. But keep in mind, there is likely a larger population out there with undiagnosed GRIN2B changes, so the phenotype and prognosis will continue to evolve.
What can I do to help?
We have submitted the necessary paperwork to be recognized as a non-profit organization by the United States Government. Once approved, our mission will be to help raise money for treatments and awareness for persons with GRIN2B changes. Please follow our Facebook page for updates on our non-profit status and additional ways to help.