fragile x syndrome

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.

bibliography

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