What is Fragile X Syndrome?

Fragile X Syndrome is a condition that affects around 1 in 8000 females and 1 in 4000 males. The condition is usually more severe in males and it affects cognitive development and causes learning disabilities.

Symptoms of Fragile X Syndrome (FXS)

Physical appearance

Those with Fragile X Syndrome often have protruding or large ears, an elongated face and low muscle tone (hypotonia). They can also have flat feet, a high-arched palate and larger than average testes. In terms of joints, their fingers and thumbs are hyperextensible. However, it is not an obvious condition and many cases are not diagnosed until adolescence.

Signs in early childhood

Children with Fragile X Syndrome often suffer from recurrent ear infections and sinusitis. They may also have speech difficulties. Many characteristics of FXS also meet the criteria for autism. For example, poor social development and difficulties with understanding facial expressions.

Males V. Females

Since females have two X chromosomes (of which only one will be ‘fragile’), they are usually less affected than males. Males will usually present with severe symptoms.

Intellectual development

There are varying degrees of intellect amongst those with FXS. Males have an average IQ (Intelligence Quotient) of 40, which is categorized as a severe mental disability. Females, since they’re less affected, will have IQs bordering on normal or borderline learning difficulties.

The main issues and difficulties that people with FXS present are with their short-term memory and their working memory. They also struggle with visual and spatial relationships.

If an individual has FXS and autism they usually have a lower IQ.

Fragile X Syndrome and Autism

In a lot of cases, FXS and autism coincide. It is suspected that autism is caused by genetics in these instances. Between 15-60% of people with FXS have ASD. The great variation is due to how it is diagnosed.

FXS and social interaction

People with Fragile X Syndrome often have social anxiety. This is apparent through their lack of good eye contact, them averting their gaze, the difficulties they have in forming relationships with peers. This is one of the most common problems associated with FXS. Individuals tend to struggle with social interaction when they are in unfamiliar situations.

FXS and mental health

The majority of male sufferers of FXS have ADHD (Attention Deficit Hyperactivity Disorder) along with 30% of female sufferers. This is, therefore, the most commonly diagnosed psychiatric disorder among individuals with FXS.

There are a small number of individuals with FXS who have OCD (obsessive-compulsive disorder) although many individuals have obsessions. However, since these obsessions are most often pleasurable to the individual, they are not problematic.

Neurological problems

Between 10 and 40% of individuals with Fragile X Syndrome develop seizures. These seizures are mostly partial seizures and are not very frequent. Also, from age 40 plus, men with FXS often begin having problems with their working memory.


One if 5 women who carry the Fragile X premutation go through early menopause – this is defined as menopause before age 40. Women with the full FXS mutation don’t have premature menopause as often as carriers do.

Treatment of Fragile X Syndrome

Treating the disorder is often done via the treatment of symptoms that are from secondary characteristics that are associated with FXS.

The most common symptoms that are treated included medication that treats hyperactivity, attentional problems and impulsivity. Problems with mood are usually treated by SSRIs (serotonin reuptake inhibitors). In individuals with aggressive or aberrant behaviour, antipsychotic medications are issued. For sufferers of associated seizures or mood swings, anticonvulsants are prescribed.

The life expectancy of individuals with Fragile X Syndrome

Individuals with FXS have an average life expectancy that is around 12 years lower. The causes of death of individuals with Fragile X Syndrome are no different on the whole to the general population.

Diagnosing Fragile X Syndrome

FXS is diagnosed by a blood test which looks at the DNA. The gene responsible for Fragile X was discovered in 1991.

Why is diagnosis important?

There are two reasons why it is important to get a diagnosis for Fragile X Syndrome. Firstly, by acknowledging the condition, an individual can get appropriate help with speech, language, behaviour and education. For adults, it can help them to understand and manage some of their difficulties. Secondly, if you have a diagnosis for Fragile X Syndrome, it also means your relatives could be affected, even if they are just carriers. Family members, including children, might benefit from being tested and having genetic counselling.

The testing procedure for FXS

A family GP or a paediatrician is usually the person who will complete a referral for a DNA blood test to test for Fragile X. The individual will give a sample of blood which will then be tested at a genetics centre. Results of DNA testing usually become available between 6 and 8 weeks. You may be given results in the form or a letter, over the phone or in a face to face appointment.