Fragile X syndrome, also termed Martin-Bell syndrome or marker X syndrome, is the most common cause of inherited mental retardation. Fragile X syndrome has been found in all major ethnic groups and races, and is caused by an abnormality (mutation) in the FMR1 gene. FMR1 is a gene located . Fragile X syndrome is caused by the expansion or lengthening of the FMR1 gene on the X chromosome, known as a gene mutation. The X chromosome is one.

Author: Dak Grorisar
Country: Laos
Language: English (Spanish)
Genre: Education
Published (Last): 18 December 2004
Pages: 330
PDF File Size: 15.98 Mb
ePub File Size: 6.66 Mb
ISBN: 350-9-88525-170-7
Downloads: 65198
Price: Free* [*Free Regsitration Required]
Uploader: Samurisar

American Journal of Medical Genetics. Very rarely females will present with this syndrome. This technique is no longer used in the diagnosis of this syndrome because it is both less accurate and costlier than are molecular techniques.

Some current clinical trials also are posted on the following page on the NORD website: Some girls have no signs at all. Pairs of human chromosomes are numbered from 1 through 22 and the sex chromosomes are designated X and Y.

All studies receiving U. FMRP is found throughout the body, but in highest concentrations within the brain and testes. If an individual is diagnosed with FXS, genetic counseling for testing family members at risk for carrying the full mutation or premutation is a critical first-step.

However, their children are at increased risk because the premutation may be unstable when transmitted to the next generation. With educational efforts, therapy, and support, all individuals with fragile X syndrome can make progress.

FMRP is involved in making connections between neurons nerve cells in the brain. This causes the symptoms of Fragile X. Am J Intellect Dev Disabil. A genetic blood test can diagnose Fragile Z. FXS is caused when this gene lengthens to over repeats interfering with the normal production of this protein and therefore normal brain development.


For a detailed discussion of Treatments and Interventions please go to the National Fragile X Foundation website https: Autism spectrum High-functioning autism Classic Autism Asperger syndrome Pervasive developmental disorder not otherwise specified Childhood disintegrative disorder Rett syndrome.

Fragile X syndrome is a rare or orphan disease which affects 1 in males and 1 in females. Retrieved 10 May Although individuals with FXS have difficulties in forming friendships, those with FXS and ASD characteristically also have difficulties with reciprocal conversation with their peers.

Fragile X syndrome – Wikipedia

Fragile X syndrome is the most common form of inherited developmental disability. Together we are strong.

Curr Neurol Neurosci Rep. Fraijl of translation and posttranslational modification. Unlike many genetic diseases, it may not be apparent that a person has Fragile X.

Rare Disease Database

In contrast, female offspring whose fathers have a premutation always inherit it and thus grandchildren of males with the premutation are at risk to have fragile X syndrome. Repeat expansion is considered to be a consequence of strand slippage either during DNA replication or DNA repair synthesis. The effect of FMR2 genes with copies of CCG has not yet been determined likely because the disorder has a mild clinical presentation.

Few studies suggested using folic acid, but more researches are needed due to the low quality of that evidence. Not all individuals with a premutation will develop FMR1 — Related disorders, but having a premutation frajkl the risks for developing these.

Although only a minority will meet the criteria for obsessive—compulsive disorder OCD frjil, a significant majority will feature obsessive-type symptoms. Archived from the original on Archived from the original on 12 October Some drugs, originally developed to treat other disorders, were shown to be effective in treating symptoms of fragile X syndrome in the animal models but when used on human subjects appeared to be less effective.

Drugs of the Future. It appears that individuals with FXS are interested in social interaction and display greater empathy than groups with other causes of intellectual disability, but display anxiety and withdrawal when placed in unfamiliar situations with unfamiliar people. However, monitoring is required for metabolic side effects including weight gain and diabetes, as well frajl movement disorders related to extrapyramidal side effects such as tardive dyskinesia.


Children with fragile X have very short attention spans, are hyperactiveand show hypersensitivity to visual, auditory, tactile, and olfactory stimuli.

Most of these mRNA targets have been found to be located in the dendrites of neurons, and brain tissue from humans with FXS and mouse models shows abnormal dendritic spineswhich are required to increase contact with other neurons.

fraji, Developmental Disabilities Research Reviews. Martin-Bell syndrome, [1] Escalante syndrome. Expanded CGG-repeat alleles of the fragile X gene”. Luke Priddis Foundation Australia. The Journal of Neuroscience. Fragile X tremor-ataxia syndrome FXTAS is characterized by a progressive adult-onset movement abnormalities ataxia and rhythmic, involuntary movements tremors that affect mostly men. Alexithymia Attention deficit hyperactivity disorder Anxiety disorder obsessive—compulsive disorder Late talker Epilepsy Fragile X syndrome Hyperlexia Savant syndrome Sensory processing disorder Intellectual frxjil Developmental coordination disorder Multiple complex developmental disorder.

X-linked spinal muscular atrophy 2 E3: When greater than repeats are d, abnormal chemical changes occur in FMR1 called methylation. Females with the abnormal gene may be affected by this disorder. Public health literature review of fragile X syndrome.

In addition, FMRP has been implicated in several signalling pathways that are being targeted by a number of drugs undergoing clinical trials. Haemophilia A Haemophilia B X-linked sideroblastic anemia.