Why Fragile X, Autism Patients Shun Physical Contact

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Fragile X syndrome is a genetic defect that is the best-known cause of autism. New research from the Northwestern University Feinberg School of Medicine has found a delayed development in the brain that may be responsible for the reason why those with the condition avoid hugs and physical contact, even from those they love.

Fragile X syndrome is caused by a gene mutation in the X chromosome that interferes with the production of a protein called fragile X mental retardation protein (FMRP) that directs the formation of other proteins that build synapses in the brain. Patients with the defect have a broken or kinked X chromosome causing a decrease in the production of the FMRP protein.

Anis Contractor, assistant professor of physiology at Feinberg and lead investigator of the study, found that for those with the defect, the part of the brain that is responsible for response to touch, called the sensory cortex, is slower to develop during a critical period of growth when the brain is very plastic and rapidly changing. If the elements of the rapid development are uncoordinated, the brain is wired incorrectly and cannot function properly.

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Scientists are hoping with this new finding that they can identify the window of opportunity to provide therapeutic intervention that can correct the improper synapse development, the sites where the neurons in the brain communicate with each other, so that they may be able to reverse some of the symptoms of the disease. A study from the University of Edinburgh discovered recently that the changes in the brain’s connections occur about midway through a baby’s development in the womb.

Patients with Fragile X syndrome have debilitating sensory problems, as well as cognitive issues such as mental retardation. They have what Contractor calls “tactile defensiveness”, where they do not look into people’s eyes, won’t hug even their parents, and they are hypersensitive to touch and sound. The resulting social withdrawal and anxiety shows up even in early infancy and progressively worsens throughout childhood.

Boys are often more affected than girls, because they only have one X chromosome while girls have two.

The study was published in the February 11th issue of the journal Neuron.

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