1. Fragile X Syndrome (FXS)
Helena Bui

2. Introduction to FXS
James Martin, Julia Bell - British physician and geneticist
1943 – X-linked pedigree related to mental disability
Martin-Bell Syndrome , Marker X Syndrome
Genetic condition  developmental problems, learning disabilities, behavior/mental challenges
No racial/ethnic bias
Most common in males
1 in 4,000 males vs. 1 in 8,000 females
Mutation in FMR1 gene

3. James Martin and Julia Bell

4. Cause/Inheritance Cause – FMR1 gene on X chromosome
DNA segment (CGG triplet) expanded/repeated
5 to 40 times vs (to 1000) times repetition
Expansion  silences FMR1  loss of fragile X mental retardation protein production (FMRP)
Development of connections between nerve cells
55 to 200 repeats = FRM1 gene premutation, normal but lower amount of FMRP
Inheritance – X-linked dominant
Mutant gene - on X chromosome
Dominant – one copy = enough to cause condition
Males XY vs. female XX  males have no extra cover up X  impact more severe
Normal, premutation and full mutation
Males more affected, only one X

5. Cause/Inheritance (Pictures)
First picture  repeated CCG triplet expansion, differences bewteen normal, premutation and full mutation
Second below  location of FMR1 gene on X chromosome
Third right  X-linked inheritence

6. Symptoms Male impact more severe than female
Delayed development of speech and language by 2
Tremors, poor coordination, fidgeting, anxiety
Mental disabilities  ADD/ADHD, social features of autism, seizures
Males: large ears, long face, macroorchidism, connective tissue problems, flat feet, soft skin,
Females: 1/3 affected  with significant learning disability
Most have moderate symptoms
Small percent: no apparent signs at all
Behavioral and mental skills affected
Macroorchidism – abnormally large testes

7. Diagnosis Few outward signs in infancy large circumference of head
Facial characteristics
Signs of mental retardation (especially for females) – cognitive/motor skill delay
Prenatal diagnosis with family history of FXS
PCR Test (polymerase chain reaction)
Short sequence of DNA analysis, amplify sections
Looks for expanded mutation (triplet repeat) in FMR1
Blood sample

8. Treatment No specific treatment, no cure
Supportive therapy for affected individuals
Special education
Decreased stimulation for behavior problems (ADD, ADHD)
Vocational/occupational training
Highest functioning level as possible
Occupational, behavioral

9. Summary X-Linked dominant disorder
Affects males more severely  1 X chromosome
FMR1 gene mutation  CGG triplet expansions 200 or more times
Silences FMR1 and no FMRP = mental disabilities
Behavioral problems
Not easily detected outwardly, rely on PCR test
No specific cures/treatment but many therapies

10. Works Cited
Board, A.D.A.M. Editorial. Fragile X Syndrome. U.S. National Library of Medicine, 09 June Web. 28 Nov
"FMR1." - Fragile X Mental Retardation 1. N.p., n.d. Web. 26 Nov <
"Fragile X Syndrome." - Genetics Home Reference. N.p., n.d. Web. 27 Nov < x-syndrome>.
"Fragile X Syndrome." National Fragile X Foundation RSS. N.p., n.d. Web. 27 Nov x-associated-disorders/fragile-x-syndrome/.

11. Works Cited (continued)
"GeneFacts." GeneFacts. N.p., n.d. Web. 28 Nov <
"Google Images." Google Images. N.p., n.d. Web. 03 Dec <
"Learning About Fragile X Syndrome." Learning About Fragile X Syndrome. N.p., n.d. Web. 27 Nov <
"Who Discovered Fragile X Syndrome?" Who Discovered Fragile X Syndrome? N.p., n.d. Web. 28 Nov < syndrome/>.