The fragile X syndrome is the
leading genetic cause of mental retardation. It is caused by a change in DNA
(deoxyribonucleic acid abbreviation), or in the genetic information of a gene
called FMR1.Este gene is located on chromosome X, which is a sex chromosomes.
Women usually have two X chromosomes (XX) and men usually have one X chromosome
and one Y chromosome (XY).
In people with Fragile X syndrome, a genetic disorder is the excessive repetition of a certain sequence of the genetic code of the FMR1 gene consists of three "letters" (CGG). The normal number of repetitions is between 5 and 54. When there is an expansion of this region of the gene, the protein FMR1, which is very important for the normal functioning of the nervous system stops being produced by the FMR1 gene.
Depending on the number of CGG repeats in fragile X syndrome can present a variety of physical manifestations, intellectual and behavioral. People with more repeats tend to have more severe manifestations. For example, people with 200 or more CGG repeats have a complete and fragile X mutation, in general, develop many of the manifestations of fragile X syndrome, including mental retardation. People with 55-200 CGG repeats have what is known as fragile X pre-mutation and show no obvious signs or symptoms of fragile X syndrome. The number of CGG repeats may increase when the gene is passed from one generation to the next generation. If the mother is a carrier of a pre-mutation, the probability of their sons or daughters come to present the full mutation is very large, whereas if the father carries a pre-mutation, this probability is very low.
The fragile X syndrome is the cause hereditary (familial) more frequent mental retardation, manifesting itself in approximately 1 in every 4.000 to 6.000 men and 1 in 8.000 to 9.000 women. However, the number of people who have genes with pre-mutation, showing no signs or symptoms of the syndrome, is superior.
Treatment
There is no way to correct or remove the extra CGG repeats causing the fragile X syndrome. Treatment focuses on relieving symptoms and maximizing the potential of each child. This can include:
• A special education program with modifications in the environment of the classroom, teaching materials and curriculum
• Psychological counseling for the affected child and his family
• Occupational therapy and speech therapy
• Medication to treat hyperactivity, difficulty concentrating, aggression and other behavior problems
• Vocational training and, if indicated, placement in a residence with adequate support in the case of adolescents and adults with cognitive impairment
The new treatment approaches are based on research studies that show changes in brain function relating to the activity of the protein FMR1. Changes in gene FMR1 change the way nerve cells "talk" to each other in the brain and scientists are studying drugs that may correct this communication breakdown.
Prevention
Family members of people affected with fragile X syndrome may carry genetic counseling and, if indicated, genetic testing for information about their risk of transmitting the mutation to their children.
If a parent knows that bears a pre-mutation, it is possible to detect early disease in the offspring. Genetic testing may be done on the fetus during pregnancy, or in the embryo before being implanted. In the latter case, it is necessary to resort to assisted reproductive techniques.
In people with Fragile X syndrome, a genetic disorder is the excessive repetition of a certain sequence of the genetic code of the FMR1 gene consists of three "letters" (CGG). The normal number of repetitions is between 5 and 54. When there is an expansion of this region of the gene, the protein FMR1, which is very important for the normal functioning of the nervous system stops being produced by the FMR1 gene.
Depending on the number of CGG repeats in fragile X syndrome can present a variety of physical manifestations, intellectual and behavioral. People with more repeats tend to have more severe manifestations. For example, people with 200 or more CGG repeats have a complete and fragile X mutation, in general, develop many of the manifestations of fragile X syndrome, including mental retardation. People with 55-200 CGG repeats have what is known as fragile X pre-mutation and show no obvious signs or symptoms of fragile X syndrome. The number of CGG repeats may increase when the gene is passed from one generation to the next generation. If the mother is a carrier of a pre-mutation, the probability of their sons or daughters come to present the full mutation is very large, whereas if the father carries a pre-mutation, this probability is very low.
The fragile X syndrome is the cause hereditary (familial) more frequent mental retardation, manifesting itself in approximately 1 in every 4.000 to 6.000 men and 1 in 8.000 to 9.000 women. However, the number of people who have genes with pre-mutation, showing no signs or symptoms of the syndrome, is superior.
Treatment
There is no way to correct or remove the extra CGG repeats causing the fragile X syndrome. Treatment focuses on relieving symptoms and maximizing the potential of each child. This can include:
• A special education program with modifications in the environment of the classroom, teaching materials and curriculum
• Psychological counseling for the affected child and his family
• Occupational therapy and speech therapy
• Medication to treat hyperactivity, difficulty concentrating, aggression and other behavior problems
• Vocational training and, if indicated, placement in a residence with adequate support in the case of adolescents and adults with cognitive impairment
The new treatment approaches are based on research studies that show changes in brain function relating to the activity of the protein FMR1. Changes in gene FMR1 change the way nerve cells "talk" to each other in the brain and scientists are studying drugs that may correct this communication breakdown.
Prevention
Family members of people affected with fragile X syndrome may carry genetic counseling and, if indicated, genetic testing for information about their risk of transmitting the mutation to their children.
If a parent knows that bears a pre-mutation, it is possible to detect early disease in the offspring. Genetic testing may be done on the fetus during pregnancy, or in the embryo before being implanted. In the latter case, it is necessary to resort to assisted reproductive techniques.
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