Shining a spotlight on rare genetic conditions: 16p11.2

Our bodies are comprised of trillions of cells. Within these cells are microscopic structures such as ribosomes, cytoplasm, nucleus, mitochondria, etc.

Our genetic material, i.e. the thing that makes us ‘unique’ from others, resides within a cell's nucleus and mitochondria. It is stored in the form of DNA within thread-like structures called chromosomes, of which we each have 23 pairs.

Some individuals, however, may have too much or too little of this genetic material; small segments of it can be deleted or duplicated which results in interference with normal development, such as leading to 16p11.2 deletion or duplication syndrome. These small segments of DNA that are lost or duplicated are referred to as copy number variants (CNV’s)

So, what is 16p11.2 deletion and duplication syndrome?

The 16 refers to the chromosome number (remember, we have 23 pairs), so this tells us these syndromes affect chromosome 16. The 11.2 refers to the location on chromosome 16: our chromosomes are made up of both light and dark bands which are numbered from the centre, so the 11.2 tells us that it is located at band number 11.2. Thus, people with 16p11.2 deletion syndrome are missing a segment of genetic material at location 11.2 on chromosome 16, whereas those with 16p11.2 duplication syndrome have an extra copy of this small segment of genetic material at location 11.2.

Some features commonly observed amongst 16p11.2 deletion and duplication syndrome include low muscle tone, variable head circumference, developmental delay, increased risk of seizures and difficulties with speech and language development.

Though 16p11.2 is considered to be a rare genetic condition, it is increasingly being diagnosed within clinical settings due to advances in genetic technologies. The 16p11.2 deletion is estimated to affect 4 in 10,000 individuals, and the duplication affects 5 in 10,000 individuals. Though we know that gene alterations at 16p11.2 can contribute to human health problems, more research is needed to better clinicians’ awareness to the recognition, diagnosis, and implementation of early interventions of such genetic conditions.

Connecting researchers and families impacted by 16p11.2

With this in mind, Ebony Jones and Tayla-Jeanne Barford, Cardiff University placement students in the Centre for Neuropsychiatric Genetics and Genomics, developed an awareness campaign through Facebook  to contribute to the understanding and awareness of 16p11.2, 16p11.2 Research and Resources.

Ebony said, "We wanted to create a community where families can share their experiences of 16p11.2, be aware of the ongoing research at Cardiff University and most importantly, gain an insight into 16p11.2 deletion and duplication syndromes.

"As November is 16p11.2 awareness month, we decided to post every day for the first 16 days with the hope of spreading awareness and educating families across the country. And we did exactly that, our page has grown tremendously since we first began with families from the UK, the US and Canada sharing their experiences as well as their gratitude of our research and resources. Each post presents information from published research and clinical resources in a visual format to aid understanding."

The Centre for Neuropsychiatric Genetics and Genomics at Cardiff University has been researching 16p11.2 deletion and duplication syndromes for over 10 years under the leadership of Prof Marianne van den Bree.

Previous international research led by Cardiff has established that 16p11.2 deletion and duplication syndromes are associated with a range of psychiatric outcomes.

One of the most recent projects looking at 16p11.2 is the STEER project, led by Medical Research Foundation Fellow Dr Samuel Chawner. The STEER project will investigate the presence of disordered eating in 16p11.2 deletion and duplication syndromes. It is already known that adults with 16p11.2 deletion are at increased risk of being overweight and adults with the 16p11.2 duplication are at increased risk of underweight, but it is not known whether disordered eating in childhood is driving these extreme weight outcomes.

The STEER project on eating behaviour in 16p11.2 deletion and duplication syndromes is funded by the Medical Research Foundation.