Fragile X Syndrome By: Isabelle White

Fragile X syndrome is a genetic condition that causes a range of developmental problems including learning disabilities and cognitive impairment. Usually, males are more severely affected by this disorder than females.

Fragile X Syndrome in males is approximately 1 in 3,600 to 4,000 and in females is approximately 1 in 4,000 to 6,000. The reason why it is lower in females is that, while all males with an FMR1 full mutation will have Fragile X syndrome, some females with an FMR1 (The Fragile X (FMR1) Gene) full mutation will not have behavioural, cognitive or physical features of Fragile X Syndrome.

Signs and symptoms of the disorder:

Behavioural and Emotional features: Anxiety and shyness, Attention Deficit Hyperactivity Disorder (ADHD), Autistic type behaviours, Difficulty with eye contact, Tactile defensiveness, Repetitive speech, Aggression

Developmental features: Intellectual disability, Learning difficulties, Developmental delay, Speech and communication difficulties, Difficulty with coordination, Difficulty with fine and gross motor skills

Physical features: Physical features may be subtle or not present they can include, Low muscle tone and loose joints, Long narrow face, prominent ears (in older males), High palate, Large testicles (in post pubescent males), Mitral valve prolapse (heart murmur)


Fragile X syndrome is inherited in an X-linked dominant pattern. A condition is considered X-linked if the mutated gene that causes the disorder is located on the X chromosome, one of the two sex chromosomes. (The Y chromosome is the other sex chromosome.) The inheritance is dominant if one copy of the altered gene in each cell is sufficient to cause the condition. X-linked dominant means that in females (who have two X chromosomes), a mutation in one of the two copies of a gene in each cell is sufficient to cause the disorder. In males (who have only one X chromosome), a mutation in the only copy of a gene in each cell causes the disorder. In most cases, males experience more severe symptoms of the disorder than females.

location of the gene:

The disorder is located on the X chromosome.

Type of tests can be done to identify the disorder:

A diagnosis of Fragile X is made through a DNA blood test. You can organise the test though your GP or paediatrician or any medical doctor. The blood can be collected by your doctor or a pathology centre. Test results are usually available approximately 4 to 8 weeks after the sample is taken but the time taken can vary. The test that is required is DNA studies for Fragile X syndrome. Five to ten millilitres of blood will be collected into a lithium heparin or EDTA tube. Your your doctor will check which anticoagulant is required by the laboratory. The blood is then transported immediately without freezing.

Life expectancy of Fragile X Syndrome:

Often symptoms begin around age 60 with a tremor, followed several years later by ataxia. One study of 55 men with FXTAS found that from the time symptoms begin, additional life expectancy ranged from 5 to 25 years. About 20 percent of women with a permutation experience premature ovarian failure (POF), in which their menstrual periods stop by age 40. Only 5 to 10 percent of women with premature ovarian failure will be able to have children.


Currently there is no cure for Fragile X, but there are effective treatments that may improve quality of life and help a person reach their full potential. Psychological, occupational, physical, special education and speech therapies can be incorporated as appropriate and in a coordinated and integrated approach.


Fragile X syndrome (FXS) is slowly becoming the most common cause of inherited mental impairment in children in India. The issue of concern is that in developed countries such as the US, children between 36 and 42 months of age are detected with FXS whereas, it is diagnosed at 6 to 8 years of age in India. This leads to a huge gap in their treatment cycle. Approximately 1 in 3,000 to 4,000 individuals has FXS. Usually, males are more severely affected by this disorder than females and generally with greater severity. Life expectancy is not affected as there are usually no life-threatening health concerns associated with the condition.


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Isabelle White

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