Rates of Autism in Fragile X syndrome

Rates of Autism in Fragile X syndrome (FXS)

FXS OVERVIEW
* Fragile X syndrome (FXS), also called Martin-Bell syndrome, is the most common type of inherited intellectual disability
* An inherited condition that is passed down from parents to child, due to a single gene mutation. The abnormal gene is located in the X chromosome.
* About one out of 4,000 males and one out of 8,000 females are born with FXS each year in the United States.
* Mothers with the mutation have 50% chance of passing the gene to their children of both sexes, whereas fathers can only pass it to their daughters.
* Severity of the condition depends on the number of gene repetition.
* patients with FXS experience some combination of symptoms that affect their mental, physical, social, and sensory characteristics. Females with FXS often experience milder symptoms than males.

(http://www.wellness.com/reference/conditions/fragile-x-syndrome-fxs/symptoms-and-causes)

GUILTY GENE
* One in 250 females and 1 in 500 males carries the FMRl gene in a pre-mutation state.
* Located on the long arm of chromosome X, in the q 27.3 region.

CHARACTERISTICS OF FRAGILE X SYNDROME
* FXS has different effects on males and females. Males tend to be more affected than females.
* Intellectual disabilities. ranging from mild to severe. Low IQ score (40-75 for males). Female’s intellectual abilities is considered mild to moderate ,to a relatively normal mental development .
* Physical characteristics:
* elongated face or jaw
* larger ears,
* short stature
* Physical characteristics are usually normal for infants and young children.
* They become noticeable around the 11th year, and become clearly distinct during puberty.
* http://www.wellness.com/reference/conditions/fragile-x-syndrome-fxs/symptoms-and-causes

CHARACTERISTICS OF FRAGILE X SYNDROME
* Social and emotional disabilities:
* Anxiety which leads to avoidance behavior and health issues (heart palpitations, faintness, blushing, and profuse sweating)
* Attention deficit
* Anger issues
* Aggressive behaviors (males)
* Language development: Males and females have different language development
* Difficulty understanding social cues, body language, tone of voice, or facial expressions

CHARACTERISTICS OF AUTISM
* Autism is a behavioral diagnosis with no bio-marker.
* Impaired social interaction
* Impaired communication
* Restricted interests
* Repetitive behaviors

PREVALENCE OF FXS IN AUTISM
* FXS can cause a child to have to have Autism or ASD. However not all children with FXS have Autism
* Between 2% and 16% of all children diagnosed with autism.
* Approximately one-third of all children diagnosed with fragile X syndrome also have some degree of autism.
* Fragile X syndrome is the most common known single gene cause of autism (http://www.fragilex.org/html/autism_and_fragile_x_syndrome.htm)

DIFFERENCES BETWEEN FXS AND AUTISM
FXS differs from autism in that it can be defined in terms of a specific biomarker: an abnormally expanded sequence of CGG repetitions at the fragile X site at Xq27.3. There is, however, a wide range of individual differences in the length of this triplet expansion, the completeness of the resulting DNA methylation, the levels of transcription and translation into FMR1 mRNA and FMRP, and the modulator effects of polymorphisms in the many genes whose products FMRP regulates.

REFERENCES

* Thomas Johnson, Vanessa A. Checklist Assessments Of FMRl Gene Mutation Phenotypes. Journal of Diversity, Vol, 15, No, 3 Fall 2008
* Belmonte, Matthew K & Bourgeron, Thomas. Fragile X Syndrome and Autism at the Intersection of Genetic and Neural Networks. Nature Neuroscience, Vol 9, No 10, October 2006.
* Feinstein, Carl and Reiss Allan L. Autism: The Point of View from Fragile X Studies. Journal of Autism and Developmental Disorders, Vol. 28, No. 5, 1998
* Brodkin,Edward S. Social Behavior Phenotypes in Fragile X Syndrome, Autism, and the Fmr1
Knockout Mouse: Theoretical Comment on McNaughton et al. (2008). Behavioral Neuroscience /American Psychological Association, 2008, Vol. 122, No. 2, 483–489.
* fragilex.org
* http://www.wellness.com/reference/conditions/fragile-x-syndrome-fxs/symptoms-and-causes


Rates of Autism in Fragile X syndrome (FXS).ppt