fragile x syndrome

by georgia jarmolkiewicz

Causes

caused by an alteration (mutation) in the FMR1 gene where a DNA segment (known as the CGG triplet repeat) is expanded.

  • Usually, this DNA segment will be reproduced from 5 to about 40 times.
  • In people with fragile X syndrome, the CGG segment is repeated 200+ times.
  • The abnormally expanded CGG segment inactivates (silences) the FMR1 gene, which prevents the gene from producing a protein called fragile X mental retardation protein.
  • Loss of this protein leads to the symptoms.
  • Both boys and girls can be affected
  • Because boys have only one X chromosome, a single fragile X is likely to affect them more

 

Those Most Affected

  • most common form of inherited mental retardation in males
  • mainly affects males
  • 1 in 4,000 males and 1 in 8,000 females
  • occurs in all racial and ethnic groups

 

Symptoms

GIRLS

  •  mental retardation
  • premature menopause or difficulty becoming pregnant.

BOYS

  • large head size, a long face, prominent forehead and chin and protruding ears
  • loose joints (joint laxity), and large testes (after puberty)
  • hyperactivity, hand flapping, hand biting, temper tantrums and autism
  • after they have reached puberty, further problems include poor eye contact, perseverative speech, problems in impulse control and distractibility
  • increased chance of eye, orthopedic, heart and skin problems.

 

How Disease is Connected to Other Body Systems

  • Nervous system mainly affected, involuntary actions are common and invasive (eg, spasms, hand flapping). Autism and mental retardation are common too, along with hyperactivity etc
  • Reproductive system is often damaged in women (infertility/premature menopause) and in men (enlarged testes)
  • Muscular/Skeletal system affected in boys: weak joints
  • Testing
  • Genetic material and dna can be anaylzed after child shows symptoms, as well as blood tests and cell analysis

Treatment

  • no treatment for diease, only for symptoms
  • special education
  • anticipatory management including avoidance of excessive stimulation to decrease behavioral problems
  • medication to manage behavioral issues, although no specific medication has been shown to be beneficial
  • early intervention
  • vision + hearing + connective tissue problems + heart problems when present are treated as they would be in a non-sufferer

Clinical Trials

  •  Seaside Therapeutics in Cambridge, Mass., have begun a clinical trial of a potential medication designed to correct a central neurochemical defect causing Fragile X syndrome.
  • Many programs, in 10+ US states have recently began trials as government healthcare pressure to study Fragile X in recent years has increased.
  • No studies yet have been conclusive.

some atypical symptoms of fragile x 

fragile X location on pair 23, X sex cells 

child with classic fragile x syndrome features: broad forehead, elongated face, prominent ears, slightly crossed eyes 

fragile x inheritance

CGG Repeats and the effect of this.

The higher the repeats, the higher change that the individual will suffer fragile x syndrome, and the symptoms they'll suffer

 

bibliography

  • https://www.genome.gov/19518828#al-5
  • https://fragilex.org/research/clinical-trials-opportunities-for-families/ongoing-clinical-trials-for-fragile-x/
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