Fragile X Syndrome

New genetic clues found in fragile X syndrome

Scientists have gained new insight into fragile X syndrome—the most common cause of inherited intellectual disability—by studying the case of a person without the disorder, but with two of its classic symptoms.

Jan 16, 2015
popularity139 comments 0

Fragile X syndrome (FXS), Martin–Bell syndrome, or Escalante's syndrome (more commonly used in South American countries), is a genetic syndrome that is the most common known single-gene cause of autism and the most common inherited cause of intellectual disability. It results in a spectrum of intellectual disability ranging from mild to severe as well as physical characteristics such as an elongated face, large or protruding ears, and larger testes (macroorchidism), behavioral characteristics such as stereotypic movements (e.g. hand-flapping), and social anxiety.

Fragile X syndrome is associated with the expansion of the CGG trinucleotide repeat affecting the fragile X mental retardation 1 (FMR1) gene on the X chromosome, resulting in a failure to express the fragile X mental retardation protein (FMRP), which is required for normal neural development. Depending on the length of the CGG repeat, an allele may be classified as normal (unaffected by the syndrome), a premutation (at risk of fragile X associated disorders), or full mutation (usually affected by the syndrome). A definitive diagnosis of fragile X syndrome is made through genetic testing to determine the number of CGG repeats. Testing for premutation carriers can also be carried out to allow for genetic counselling.

There is currently no drug treatment that has shown benefit specifically for fragile X syndrome. However, medications are commonly used to treat symptoms of attention deficit and hyperactivity, anxiety, and aggression. Supportive management is important in optimising functioning in individuals with fragile X syndrome, and may involve speech therapy, occupational therapy, and individualised educational and behavioural programs.

J. Purdon Martin and Julia Bell in 1943, described a pedigree of X-linked mental disability, without considering the macroorchidism (larger testicles). In 1969 Herbert Lubs first sighted an unusual "marker X chromosome" in association with mental disability. In 1970 Frederick Hecht coined the term "fragile site".

This text uses material from Wikipedia licensed under CC BY-SA

Latest Spotlight News

A single missing gene leads to miscarriage

A single gene from the mother plays such a crucial role in the development of the placenta that its dysfunction leads to miscarriages. Researchers from the Medical Faculty of Ruhr-Universität Bochum (RUB) have observed this ...

Why some cancers affect only young women

Among several forms of pancreatic cancer, one of them specifically affects women, often young. How is this possible, even though the pancreas is an organ with little exposure to sex hormones? This pancreatic cancer, known ...

New hope for cystic fibrosis

A new triple-combination drug treatment being trialled at the Mater Hospital in Brisbane could increase the life expectancy of patients with cystic fibrosis.

Gene plays critical role in noise-induced deafness

In experiments using mice, a team of UC San Francisco researchers has discovered a gene that plays an essential role in noise-induced deafness. Remarkably, by administering an experimental chemical—identified in a separate ...

How clutch molecules enable neuron migration

The brain can discriminate over 1 trillion odors. Once entering the nose, odor-related molecules activate olfactory neurons. Neuron signals first accumulate at the olfactory bulb before being passed on to activate the appropriate ...