LYCOS RETRIEVER 
Fragile X Syndrome: Individuals
built 658 days ago
Ninety-five per cent of cases of fragile-X syndrome are due to expansion in the CGG sequence. Normal individuals carry between 5 and 54 copies of CGG repeat. In normal carriers, the number of CGG repeats (the premutation) is between 55 and 200. In individuals clinically manifesting the syndrome, the CGG repeat (the full mutation) increases to 200-2000 or more. Such a large mutation is usually accompanied by hypermethylation of the DNA sequence, whereby methyl groups attach to the CGG triplets. This renders the FMR-1 gene transcriptionally inactive.
Source:
Intellectual disability is common in people who carry the Fragile X gene, although abilities do span a wide range. Approximately eighty per cent of males have learning disabilities. These are mostly in the mild to moderate range, but about one-third have severe learning difficulties. Overall, verbal abilities tend to be better than performance abilities, with relative strengths in vocabulary, aspects of simultaneous information processing, and some visual perceptual tasks. Affected individuals are much weaker on tasks of abstract reasoning, sequential processing, visual-spatial abilities and short term memory and numeracy. They tend to have greater difficulty in processing new information than in learning school-related, verbally-based factual material.
Source:
Individuals with fragile X syndrome appear normal at birth, but their development is delayed. Most boys with fragile X syndrome have mental impairment. The severity of mental impairment ranges from learning disabilities to severe mental retardation. Behavioral problems include attention deficit and hyperactivity at a young age. Some may show aggressive behavior in adulthood. Short attention span, poor eye contact, delayed and disordered speech and language, emotional instability, and unusual hand mannerisms (hand flapping or hand biting) are ... seen frequently.
Source:
Autistic-like behaviours have been reported in individuals who have fragile X syndrome. These include avoidance of eye contact, stereotyped repetitive behaviours such as hand flapping, repetitive speech, resistance to environmental change, and strong preoccupations or fascinations. Only a minority of individuals have 'typical' autism. Most are affectionate and have an interest in relating socially, but have notable difficulties in social interactions and tend to be shy and anxious in social situations. Also, while affected individuals do repeat their own and other people's speech, these repetitions are believed to serve an important communicatory function, since they maintain participation in conversation while the individual is trying to process what is being said. Affected individuals are easily overwhelmed by a variety of sensory stimuli, which they find difficult to cope with.
Source:
Behaviors in postpubertal males with fragile X syndrome often include tactile defensiveness, poor eye contact, perseverative speech, problems in impulse control, and distractibility. The behaviors tend to become more obvious over time. The comorbid diagnosis of autism occurs in nearly 25% of affected individuals [Hatton et al 2006].
Source:
Psychology professionals warn against the tendency to assume that all characteristics of a child with Fragile X stem directly from the Fragile X syndrome. The emotional difficulties of an individual with Fragile X may include insecurity and anxiety related to having a disability.
Source:
MORE ABOUT
Individuals