By Jonathan Learmont
Hindering the development of cognitive abilities and influencing behaviour, Fragile X syndrome is the most common cause of inherited learning difficulties and affects around 1 in 5000 males and 1 in 8000 females. The genetic disorder is caused by an elongated mutation of the FMR1 gene, where the trinucleotide CGG repeats over 200 times when between 6 and 54 is usual. This means the production of the FMRP protein in the body instructed by FMR1 does not occur. As this protein is crucial in brain development, Fragile X syndrome sufferers typically have lower IQs later in life and develop language and speech skills more slowly than normal. This sometimes causes ADHD in childhood as staying focused is more difficult. Most males and around half of females can be distinguished by physical features such as prominent ears and jawbones, as well as a long narrow face.
The difference between male and female rates is as a result of the FMR1 gene appearing on the X chromosome, so females have a copy of the gene that may not be mutated while males don’t. Consequently, almost all males experience learning difficulties while these tend to occur at a lower rate and be less severe for females.
Fragile X syndrome also shares characteristics of autism in its effects on sociability such as increased anxiety and is thought underlie around 1 in 20 autism cases overall. It has also been associated with a higher risk of epilepsy; seizures occur in 15% of males and 5% females.
There is no cure for Fragile X syndrome, and currently patients must manage their symptoms with a wide range of medication. However, research commencing in the Medical Discovery Institute at Cardiff University, to be funded by a grant of almost £2.5m by the Medical Research Council, aims to tackle the disorder more directly. Scientists hope to produce a drug that will inhibit the LIMK1 protein, which is known to be involved in the development of Fragile X syndrome.
Professor Simon Ward, Director of the Medical Discovery Institute said, “By targeting this protein, we aim to develop a novel medication that will make a difference to the lives of people living with the condition, as well as their families. We have been working closely with the Fragile X Society and the FRAXA charity to improve treatment options.”
Such a disease modifying therapy could have a profound impact on improving the lives of patients diagnosed early. It may also reassure future parents who are at risk of passing on the disorder that their children can have a good chance of living healthily.