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Fragile X is an inherited genetic syndrome, which results in learning and behavioural difficulty, associated with Autism. 

It gets its name from the discovery of an abnormal ‘fragile’ site on the X chromosome. Fragile X occurs in approximately 1 in 4,000 males and 1 in 8,000 females; its severity is more marked in boys than girls, with intellectual disability varying from mild to severe. Effects are wide-ranging and unpredictable. Fragile X accounts for 2-3 per cent of cases of Autism. 

Children with Fragile X may be developmentally delayed and experience learning and behavioural difficulties. Children may appear ‘floppy' with autistic features eg hand-flapping and poor eye-contact and have poor fine motor control. Attention difficulties are common as well as anxiety and unstable mood. 

Characteristics of Fragile X :  

  • 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 intellectual disability. 
  • Speech and language problems 
  • Challenging behaviour: Girls are usually less affected than boys but have similar attention difficulties and are often extremely shy and socially withdrawn. 
  • Emotional factors: Children with Fragile X can be easily overwhelmed, particularly in busy or stressful environments. They may suffer sensory over-stimulation, seemingly overreacting to noises, smells and sounds. They need routine, security and constant reassurance. Emotional difficulties are common even in girls with a normal IQ. 
  • Coordination and sensory issues: Fine motor co-ordination problems are common in youngsters with Fragile X but are not usually apparent until later. 
  • Over-sensitiveness to sensory stimuli means that people with Fragile X are easily overwhelmed by sights, sounds, smells, tastes and textures – poor eye contact and gaze avoidance may be attempts to avoid excessive stimulation. 

Diagnosis is by blood test using DNA analysis. Prenatal diagnosis is also possible. 

Further information:

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