People who carry certain mutations in gene CHD8, a gene strongly linked to autism, tend to be taller and have larger heads than the average person. They also tend to have intellectual disability, according to a study conducted by geneticists at Cedars-Sinai Medical Center in Los Angeles, California.
Mutations in genes linked to autism, such as CHD8, are known to influence how other genes express themselves. Previous studies looking at mutated versions of CHD8 gene have found that children carrying them have more social problems on average than those with other gene variations. While previous research has also shown that children with certain mutations in the CHD8 gene have unusually large heads however, little attention had been given to other physical characteristics also carried over as a consequence of the gene
In their study, researchers studied 21 males and 6 females with CHD8 mutations between the ages of 1 and 27. Likely the largest study observing the mutation so far, all had intellectual disability (23 within the mild or moderate range) and 23 had a head circumference, height or both in the 97th percentile of above for the age. 21 of the participants also had behavioral problems, with 15 of them either displaying autistic traits or having been clinically diagnosed with the disorder.
Alongside these characteristics, the researchers also noted other physical traits in common to small groups of participants including low muscle tone, seizures, spinal curvature, umbilical hernia, flat feet and curved pinky fingers.
Although the researchers note that these findings may not be particularly significant by themselves, their combination may be suggestive of a set of clinical features that could be referred to as CHD8-related syndrome. The researchers thus suggest that these characteristics should be considered as a differential diagnosis of autistic patients who present increased height and/or head circumference as well as intellectual disability.
Although until now the researchers have only recorded the effects of CHD8 overgrowth syndrome on the skeletal system, as head circumference usually tracks brain size, in the future, they are curious to see to what extent other organs are also affected by the gene.
Sources: Pub Med, Spectrum News May 2019 and Spectrum News December 2019