Every cell in the human body consists of a nucleus (except RBC’s and a few others) where the genetic material is stored. It carries 23 pairs of chromosomes, half of which is inherited from each parent. Down syndrome occurs when an individual has a full or partial extra copy of chromosome 21.
DS occurs in one out of every 691 live births and is the most common genetic cause of intellectual disability, affecting approximately 400,000 Americans. The underlying developmental and genetic causes of this intellectual disability in DS are not fully known and because of this lack of knowledge, no treatment is currently available.
For the first time now, researchers have identified the lifelong changes in gene expression in the brains of people born with Down syndrome (DS).
The findings, which appear in the journal Neuron, could lead to possible therapies for DS patients.
A multi-institution team of researchers led by Tarik Haydar, PhD, associate professor of anatomy and neurobiology at Boston University School of Medicine (BUSM) and Nenad Sestan, MD/PhD professor of neuroscience at Yale School of Medicine, compared gene expression in different regions of the brains of humans with Down Syndrome across development and adulthood.
They discovered that the establishment of white matter in the brain, which is the insulation of the brain nerve fibers, (i.e. axons) is altered from toddler to adult periods of development. This was an unexpected finding, especially since current theory suggests that changes leading to intellectual disability in DS patients occurred prenatally (before birth).
This change in white matter in the brain occurs due to a specific defect during developmental stages in a class of brain cells called oligodendrocytes. These cells form the white matter of the brain, and this defect causes slower nerve transmission.
“This discovery of the genetic changes that alter communication within the brain uncovered a completely new target for therapies in the brains of people with DS,” explained Haydar.
“These findings may allow researchers to design strategies to promote brain functioning and improve quality of life, he added.
The researchers also believe these findings may have profound implications for individuals with other developmental disabilities, such as autism.