Brain Develops Differently in Fragile X Syndrome

MRI scans reveal anatomical alterations in children with genetic disorder

THURSDAY, May 6 (HealthDay News) -- Brain development in very young boys with fragile X syndrome differs from that in boys without the genetic disorder, a new study has found.
Fragile X syndrome, which is triggered by a mutation in a gene on the X chromosome, is the leading cause of inherited intellectual disability and autism. Though the syndrome affects about one in every 4,000 people, males with the disorder experience more significant symptoms than females.
U.S. researchers used high-resolution MRI to monitor long-term changes that differentiated the brain anatomy of 41 boys with fragile X syndrome and a control group of 21 healthy boys and seven other children who were experiencing developmental delays not caused by fragile X syndrome.
Detailed images of the children's brains were first taken when they were 1 to 3 years old. Follow-up images were taken up to two years later. The first sets of images revealed that the children with fragile X syndrome had an overabundance of gray matter in some brain regions (caudate and thalamus) and a reduced amount of gray matter in a part of the cerebellum called the vermis.
The findings suggest that the genetic mutation had already started to cause identifiable, consistent alterations in brain development, perhaps even before birth, the study noted.
The researchers also found that other areas of the brain, such as the basal forebrain and many regions of the cerebral cortex, were the same in children with fragile X syndrome and those in the control group at the first imaging session. However, differences were seen two years later, which suggests that certain effects of the X chromosome mutation become evident only later in brain development.
The study findings were published online May 3 in the Proceedings of the National Academy of Sciences.
"A number of years ago, we saw new treatments [for fragile X syndrome] quickly coming down the line," Dr. Allan Reiss, a professor of psychiatry and behavioral sciences and radiology at the Stanford University School of Medicine and the study's senior author, said in a university news release. "We wanted to provide information that could be used to guide those treatments."
Knowing where and when fragile X syndrome affects brain development can help researchers monitor the effects of new treatments, Reiss explained.