Females with a full mutation

(see Genetics)

  1. Around 60% of females with a full mutation have cognitive deficiencies with IQ in borderline (70-84) or mild disability range.
  2. Females may also present with hyperactivity or a shy personality and some will present with selective
    mutism.
  3. Females may also have the emotional and behavioural characteristics seen in affected males.
  4. Generally speaking, affected females have a milder phenotype than affected males.
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Individuals with a premutation

(see Genetics)

  1. Premature ovarian failure
  2. Female premutation carriers have approximately 20% risk of developing premature ovarian failure
    (menopause before the age of 40 years).
  3. Fragile X tremor/ataxia syndrome (FXTAS)
  4. FXTAS is a progressive neurological disorder that usually starts after 50 years of age. It is characterised by intention tremor, cerebellar ataxia, Parkinsonism, peripheral neuropathy and dementia.
  5. Both male and female premutation carriers may develop FXTAS.
  6. The risk increases with age and in males is approximately 50% by age 79 years. Female premutation carriers are less likely to develop FXTAS; the risk is not quantifiable at this time.
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At-risk individuals

  1. Individuals of either sex with:
  2. Intellectual disability
  3. Developmental delay
  4. Autistic-like characteristics
  5. Learning disabilities of unknown cause, including borderline cases
  6. A family history of fragile X syndrome or relatives of a person with developmental delay of unknown cause.
  7. A previous fragile X cytogenetic test result that was inconclusive
  8. Consider offering fragile X DNA testing to:
  9. All individuals at risk.
  10. Adults (>50 years of age) who present with unexplained ataxia and/or intention tremor, Parkinsonism and dementia.
  11. Preconceptionally or during pregnancy to any woman with a family history of fragile X syndrome or intellectual disability of unknown cause or a family history of premature ovarian failure.
  12. Offer prenatal testing to females who are known to have a fragile X premutation or full mutation
    (see Genetics for details). Where the cause of intellectual disability has not been determined in the affected member(s) in the family, prenatal testing should be discussed and may be offered concurrently with testing of family members if time allows.
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