Fragile X

Children with Fragile X may be developmentally delayed and experience learning and emotional difficulties. Gross and fine motor skills are often poor; children may appear ‘floppy'. Adults often show strengths in domestic daily living skills, relative to their communication and socialisation abilities. Nevertheless, many need a degree of supported living.

 

It gets its name from the discovery of a link between mental handicap and an abnormal ‘fragile’ site on the X chromosome. Fragile X occurs in approximately 1 in 4,000 males and 1 in 8,000 females, and its severity is more marked in boys than girls, with intellectual disability varying from mild to severe. Effects are wide-ranging and unpredictable.

Diagnosis

Diagnosis is by blood test using DNA analysis. Prenatal diagnosis is also possible either by chronic villus or foetal blood sampling. However, prenatal diagnosis cannot always distinguish affected from unaffected carrier females. There is a 50–50 chance of a female carrier passing on the fragile X chromosome to her children. Of these, boys are almost certain to be affected whilst girls have a 1 in 3 chance of being affected. Men can also be unaffected carriers of the Fragile X chromosome, passing it to their daughters but not to their sons.

Although it was discovered in the 1970s, the gene associated with Fragile X wasn’t identified until 1991 so many individuals with the condition may remain undiagnosed. In many families a diagnosis is not made until after the birth of a second or third affected child. Carriers of the syndrome can be offered genetic counselling if appropriate. In the case of children, once a diagnosis is made, specialist help in the areas of education, speech and language development can be put in place along with any special care and understanding, appropriate medical, psychological and social help that can be given.

Problems associated with Fragile X

Not all children will have all these problems, but even those with intelligence in the average or above-average range may exhibit many of these features.

• Learning difficulties:  Approximately 80 per cent of boys and a quarter of girls with Fragile X have learning difficulties varying from subtle educational delays to severe mental handicap. Overall, strengths are verbal abilities such as vocabulary, aspects of simultaneous information processing and some visual perceptual tasks. As a result, reading is often less problematic than organising thoughts, planning ahead, processing new information (especially where abstract reasoning is involved), sequential processing, visual-spatial abilities, short-term memory and numeracy. With puberty and adolescence the rate of intellectual development appears to decline.
• Speech and language problems: Language difficulties range from a complete abs...