Study: Chromosome change points to autism

By Amanda Chan, MyHealthNewsDaily Staff Writer@myhealthnewsdaily.com

People who possess a specific change in one of their chromosomes are nearly 14 times more likely to develop an autism spectrum disorder or schizophrenia than those without this change, according to a new study.

The change, called a deletion, happens when a section of chromosome 17 is missing. The omission is found only in people with an autism spectrum disorder, a developmental delay, or schizophrenia, said study researcher David H. Ledbetter, a genetics professor at Emory University.

“This is just adding one more to that rapidly growing list of genetic mutations” associated with autism that doctors could use to measure autism and schizophrenia risk in children, Ledbetter told MyHealthNewsDaily.

Not all people with autism, a developmental delay, or schizophrenia have this deletion. But all people who have the chromosome change will develop some form of the disorder, whether it’s mild or strong enough for a diagnosis, he said.

Schizophrenia and autism are separate disorders, but other recent research has also shown the two have genetic similarities.

“At least in a subset of autism and a subset of schizophrenia, the same [genetic changes] play a major role in both,” Ledbetter said. “It will be interesting in the future, because we’ll have the ability to identify this type of deletion in young children, and follow them to figure out why some of them do develop autism and some don’t.”

The new study was published today (Nov. 4) in the American Journal of Human Genetics.

Detecting the deletion

Researchers looked in a genetic database of 15,749 people with a developmental delay, intellectual disability, or an autism spectrum disorder.

They found 18 of these people had the deletion on chromosome 17. But not one of the 4,519 healthy people tested had the deletion, according to the study.

Researchers tracked down nine of the 18 people in the database with the genetic deletion. All nine had cognitive impairments, and six of them had autism, the study said.

To confirm these findings, researchers examined two other databases with genetic information for 7,522 people with autism or schizophrenia. They found the same deletion in two people with an autism spectrum disorder or cognitive impairment and four adults with schizophrenia. None of the 43,076 healthy people tested had the deletion.

“That means the deletion has a major phenotypic effect,” Ledbetter said. “It can manifest as developmental delay, intellectual disability or autism, or it may not be diagnosed and recognized until adulthood when there are psychiatric manifestations that lead to a diagnosis of schizophrenia.”

In line with the research

Some people with the deletion also had other health problems, such as renal cysts and diabetes.

“We’re starting to appreciate now that oftentimes, when we talk about psychiatric conditions, it doesn’t really come just by itself,” said Andy Shih, vice president of science for the nonprofit Autism Speaks, who wasn’t involved with the study. “A lot of times, you see a host of other conditions that travels with autism.”

Previous work has found genes that are associated with autism. Still, these genes have “low penetrance” – meaning the genes were also found in people who don’t have any symptoms of autism, said Patricia Rodier, a professor at the University of Rochester School of Medicine and Dentistry.

“But in this case, it appears that virtually all of the people who have this anomaly of this gene have some symptoms,” said Rodier, who wasn’t involved with the study.

The new findings could be used in a genetic test that could help people confirm an autism or schizophrenia diagnosis and determine their risk of developing one of these conditions, Rodier said.

New Findings on Chromosome Deletion and Autism/Schizophrenia Risk

A recent study published in the American Journal of Human Genetics provides additional insights into the relationship between a specific deletion on chromosome 17 and the risk of developing autism spectrum disorder or schizophrenia. Led by David H. Ledbetter, a genetics professor at Emory University, the study reveals that individuals with this chromosome change are nearly 14 times more likely to be diagnosed with either autism or schizophrenia than those without the deletion.

The researchers focused on a section of chromosome 17 missing in individuals with autism spectrum disorder, developmental delay, or schizophrenia. Ledbetter explained that this discovery contributes to the growing list of genetic mutations associated with autism and provides doctors with more tools to assess the risk of these disorders in children.

Although not all individuals with autism or schizophrenia have this specific deletion, Ledbetter emphasized that anyone with the chromosome change will develop some form of the disorder, ranging from mild to severe. While schizophrenia and autism are distinct conditions, recent research highlights genetic similarities.

In examining a genetic database of 15,749 individuals with developmental delay, intellectual disability, or autism spectrum disorder, the researchers identified 18 people with the chromosome 17 deletion. Strikingly, none of the 4,519 healthy individuals tested exhibited the deletion. Further analysis of two other genetic databases, consisting of 7,522 people with autism or schizophrenia, confirmed these findings. The omission was found in two individuals with autism spectrum disorder or cognitive impairment and four adults with schizophrenia, while none of the 43,076 healthy individuals had the deletion.

By uncovering the substantial phenotypic impact of this deletion, the study emphasizes its association with developmental delay, intellectual disability, autism, and, potentially, the later onset of schizophrenia.

These findings support the notion that chromosome 17 deletion plays a significant role in both autism and schizophrenia. Ledbetter expressed interest in future research that explores why some individuals with the deletion develop autism while others do not. Additionally, the presence of other associated health conditions, such as renal cysts and diabetes, suggests a complex relationship between these disorders and other medical issues.

The study’s findings present exciting possibilities for developing a genetic test that could aid in diagnosing autism or schizophrenia and assessing an individual’s risk of developing these conditions. However, further research is needed to understand this discovery’s implications and potential applications fully.

Please note that this update is based on the information available at the time of the original study publication. For the most accurate and up-to-date information, referring to the original research and subsequent studies in the field is recommended.