'Dark genome' is involved in Rett Syndrome

Researchers at the Epigenetics and Cancer Biology Program at IDIBELL led by Manel Esteller, ICREA researcher and professor of genetics at the University of Barcelona, have described alterations in noncoding long chain RNA sequences (lncRNA) in Rett syndrome.

These molecules act as supervisor agents responsible of 'switch on' or 'switch off' other genes in our genome that regulate the activity of neurons. The work has been published in the last issue of the journal RNA Biology.

Dark genome

Only 5% of our genetic material are genes that encode proteins. The remaining 95% is known as dark genome or non-coding DNA and its function is still unknown. Part of this DNA produces RNA molecules called noncoding long chain RNA (lncRNAs).

Rett Syndrome

Rett syndrome is a neurodevelopmental disease and it is the second most common cause of mental retardation in females after Down syndrome. Clinical symptoms occur between 6 and 18 months after birth and consist of a loss of cognitive, social and motor capacities accompanied by autistic behaviors, eg, stereotypic hand movements.

Today there is no effective treatment of the disease but the control of their symptoms. The syndrome is usually due to the presence of a mutation in MeCP2 epigenetic gene that, as a magnet, regulates the expression of many other genes of the cell.

Esteller's team works with a mouse model that faithfully reproduces the characteristics of the human Rett syndrome. In this study, researchers compared the expression of long chains of RNA in healthy and diseased animals and found that the presence of mutations in the Mecp2 gene causes alterations in the activity of lncRNA.

Rett syndrome is a rare, severe, "girls only" form of autism. It's usually discovered in the first two years of life, and a child's diagnosis with Rett syndrome can feel overwhelming. Although there's no cure, early identification and treatment may help girls and families who are affected by Rett syndrome.

Who Gets Rett Syndrome?

Rett syndrome is an autism spectrum disorder that affects girls almost exclusively. It's rare - only about one in 10,000 to 15,000 girls will develop the condition.

In most cases of Rett syndrome, a child develops normally in early life. Between 6 and 18 months of age, though, changes in the normal patterns of mental and social development begin.

What Are the Symptoms of Rett Syndrome?

Although it's not always detected, a slowing of head growth is one of the first events in Rett syndrome. Loss of muscle tone is also an initial symptom. Soon, the child loses any purposeful use of her hands. Instead, she habitually wrings or rubs her hands together.