Information and Support for Carriers of fragile X
First of all, an explanation
Fragile X syndrome is the most common identifiable cause of learning disability. The gene that causes it is found at the end of the X chromosome. When viewed down a microscope this part of the X chromosome appears fragile, hence the condition’s name.
In 1991 the gene which causes fragile X was identified. This gene, called FMR1, is present in all of us and it must work properly for normal intellectual development to take place. In people affected by fragile X syndrome there is an increase in size of DNA adjacent to theFMR1 gene, which prevents it from working properly. This change in the gene is called a mutation.
A carrier is an individual who carriers an altered form of this gene which can lead to having a child or offspring in future generations with a genetic disorder.
This is a very long page containing a lot of information, so to help you access only those parts that are ofinterest to you, here is a list of the items covered below in the rest of this page:
Premutation and full mutation carriers
Female carriers with a premutation, giving details about 'Medical effects', 'Cognitive effects', and 'Social and emotional characteristics'
Female carriers with a full mutation
Male carriers with a premutation
Genetic counselling for carriers
Support and information for carriers
Information papers for carriers
Premutation and full mutation carriers
Both men and women can be carriers (also known as premutation) of the Fragile X mutation, which is caused by a small change in their gene. This small change usually does not stop the gene from working, but does make it 'unstable' . This means that the change may to increase in size when it is passed on from one genetration to the next, although this only happens when it is passed by a woman to her childen.
A premutation carrier is typically defined as an individual, male or female, who has between 55-200 CGG repeats and has a normal methylation pattern.
Both men and women can also be affected by Fragile X (also known as having the full mutation). This is due to their having a large change in their FMR1 gene. The full mutation is defined as over 200 CGG repeats with some degree of methylation. However, a female can be called a carrier when she has the full mutation when she shows little or no affects from fragile X.
Approximately one in 4,000 males and one in 6,000 females have a fragile X full mutation. Approximately one in 800 males and one in 250 females are carriers of fragile X.
Please refer to our 'Fragile X: An Introduction' booklet for a clear and precise description about the inheritence details regarding fragile X, and fragile X carrier status between the generations of a family. Please note that this booklet will be dispalyed in a pdf format in a new window.
Female carriers with a premutation
Early research findings suggested that there were few, if any, effects observed in premutation carriers; however, recent evidence suggests that some individuals with the premutation may experience medical, cognitive or social-emotional effects.
Medical effects
- Women who are premutation carriers may experience premature ovarian failure (referred to as POI, or FXPOI, or FXPOF) and an increased likelihood of twin births
- Another effect of the premutation is fragile X-associated tremor ataxia syndrome (FXTAS). FXTAS is characterized by a progressive intention tremor, ataxia, cognitive decline, and generalized brain atrophy. Although research is still very new in this area, some females with the premutation have been diagnosed with FXTAS
- In some cases women who are premutation carriers experience an early menopause, with a small proportion experiencing menopause in their 20s and 30s.This not only can make planing their families difficult but can bring with it the medical problems of menopause. Carrier women who are concerned that they are having menopausal symptoms should seek medical advice
Cognitive effects
- In general, IQ’s of females with the premutation fall into the average range although some females may have difficulties with arithmetic and vocabulary
Social and emotional characteristics
- Most women with a premutation have normal social skills although increased shyness and social anxiety can be seen in some women with the premutation. In addition, there is evidence that women with the premutation are at increased risk for major depression
Female carriers with a full mutation
A full mutation carrier would be defined as a female with over 200 CGG repeats with mild or no significant effects of the full mutation.
The physical effects associated with fragile x syndrome like long face, largish ears, joint hypermobility and other features occur in female carriers with the full mutation.
The cognitive effects can be extremely variable but specific areas of difficulty identified are executive functioning, visual-spatial awareness, non-verbal communication, mathematical computation and comprehension and visual memory.
The social-emotional effects of some fragile x females with the full mutation include depression, anxiety, shyness and social avoidance.
Male carriers with a premutation
The risk of developing FXTAS is the most significant issue for males with a premutation. The onset of this neurological condition occurs in some men over 50. The most common features are
- ataxia (balance or gait problems)
- an intention tremor (a tremor which occurs during activity- but not at rest)
- and short-term memory loss
For more information on males with the premutation please refer to ‘Fragile X Syndrome:Male Carriers of Fragile X’. Please note that this booklet will be displayed as a pdf file in a new window.
Genetic counselling for carriers
Genetic counselling is very important for all carriers of fragile X, both men and women.Genetic counsellors can give up to date information about how fragile X is passed on, and about the reproductive implications and options.
Support and information for carriers
The Family Support and Information Service provided by Jane and Wendy, our Family Support Workers, is also available to carriers. Details about the various ways in which both members and non-members can access their help and support are listed in our Contact Us page.
In the main, carriers with a fragile X premutation do not display the effects of the syndrome; however, there are a few incidences where children or adults diagnosed with the premutation have shown some effects that would normally be associated with a full mutation. If this is the case in your family or with the person you are working with then please contact Jane and Wendy (see above) for more details.
Carriers may also wish to take part in the Society's Member's Forum where they can contact other family members in order to seek friendship and share knowledge and experiences.
Carrier specific information papers
Our papers containing further information about the various issues that may be of interest to carriers of fragile X are listed below. Whereas the majority of these papers are free to family members of the Society (and carriers can be family members too, at no cost), a small charge is made for non-members to cover our reproduction costs.
- 'Talking about genetic risk to children: more than carrier testing' by Allyn McConkie-Rosell, Gail Spiridigliozzi, Elizabeth Melvin
- 'Prenatal testing for fragile X' by Barbara Carmichael
- 'Preimplantation genetic diagnosis for fragile X carriers' by Lynne Zwink
- 'Identification of the fragile X associated tremor-ataxia syndrome, known as FXTAS, in carriers of the fragile X premutation' by Lynne Zwink
- 'Clinical features of boys with fragile X premutations and intermediate alleles' by Dr Monica Aziz & Dr Jeremy Turk
- 'Male carriers of fragile X ' (booklet) - Reports the findings of the UK study of men who carry a fragile X premutation. By Dr Kim Cornish & Dr Jeremy Turk
To obtain copies of any of the papers listed above please either Contact Us or request them via the Publications Order Form, which contains details of the full range of our information about all aspects of fragile X . Please note that a new window will open for this Publications Oder Form pdf file.
See also
UK Research Reports
Current UK Fragile X Studies
Acknowledgements
The majority of the information on this page has been taken from the 'Carriers : What it means' page as at January 2009 of The National Fragile X Foundation, whose website address is
www.fragilex.org.
Information and Support for Carriers of fragile X
First of all, an explanation
Fragile X syndrome is the most common identifiable cause of learning disability. The gene that causes it is found at the end of the X chromosome. When viewed down a microscope this part of the X chromosome appears fragile, hence the condition’s name.
In 1991 the gene which causes fragile X was identified. This gene, called FMR1, is present in all of us and it must work properly for normal intellectual development to take place. In people affected by fragile X syndrome there is an increase in size of DNA adjacent to theFMR1 gene, which prevents it from working properly. This change in the gene is called a mutation.
A carrier is an individual who carriers an altered form of this gene which can lead to having a child or offspring in future generations with a genetic disorder.
This is a very long page containing a lot of information, so to help you access only those parts that are ofinterest to you, here is a list of the items covered below in the rest of this page:
Premutation and full mutation carriers
Female carriers with a premutation, giving details about 'Medical effects', 'Cognitive effects', and 'Social and emotional characteristics'
Female carriers with a full mutation
Male carriers with a premutation
Genetic counselling for carriers
Support and information for carriers
Information papers for carriers
Premutation and full mutation carriers
Both men and women can be carriers (also known as premutation) of the Fragile X mutation, which is caused by a small change in their gene. This small change usually does not stop the gene from working, but does make it 'unstable' . This means that the change may to increase in size when it is passed on from one genetration to the next, although this only happens when it is passed by a woman to her childen.
A premutation carrier is typically defined as an individual, male or female, who has between 55-200 CGG repeats and has a normal methylation pattern.
Both men and women can also be affected by Fragile X (also known as having the full mutation). This is due to their having a large change in their FMR1 gene. The full mutation is defined as over 200 CGG repeats with some degree of methylation. However, a female can be called a carrier when she has the full mutation when she shows little or no affects from fragile X.
Approximately one in 4,000 males and one in 6,000 females have a fragile X full mutation. Approximately one in 800 males and one in 250 females are carriers of fragile X.
Please refer to our 'Fragile X: An Introduction' booklet for a clear and precise description about the inheritence details regarding fragile X, and fragile X carrier status between the generations of a family. Please note that this booklet will be dispalyed in a pdf format in a new window.
Female carriers with a premutation
Early research findings suggested that there were few, if any, effects observed in premutation carriers; however, recent evidence suggests that some individuals with the premutation may experience medical, cognitive or social-emotional effects.
Medical effects
- Women who are premutation carriers may experience premature ovarian failure (referred to as POI, or FXPOI, or FXPOF) and an increased likelihood of twin births
- Another effect of the premutation is fragile X-associated tremor ataxia syndrome (FXTAS). FXTAS is characterized by a progressive intention tremor, ataxia, cognitive decline, and generalized brain atrophy. Although research is still very new in this area, some females with the premutation have been diagnosed with FXTAS
- In some cases women who are premutation carriers experience an early menopause, with a small proportion experiencing menopause in their 20s and 30s.This not only can make planing their families difficult but can bring with it the medical problems of menopause. Carrier women who are concerned that they are having menopausal symptoms should seek medical advice
Cognitive effects
- In general, IQ’s of females with the premutation fall into the average range although some females may have difficulties with arithmetic and vocabulary
Social and emotional characteristics
- Most women with a premutation have normal social skills although increased shyness and social anxiety can be seen in some women with the premutation. In addition, there is evidence that women with the premutation are at increased risk for major depression
Female carriers with a full mutation
A full mutation carrier would be defined as a female with over 200 CGG repeats with mild or no significant effects of the full mutation.
The physical effects associated with fragile x syndrome like long face, largish ears, joint hypermobility and other features occur in female carriers with the full mutation.
The cognitive effects can be extremely variable but specific areas of difficulty identified are executive functioning, visual-spatial awareness, non-verbal communication, mathematical computation and comprehension and visual memory.
The social-emotional effects of some fragile x females with the full mutation include depression, anxiety, shyness and social avoidance.
Male carriers with a premutation
The risk of developing FXTAS is the most significant issue for males with a premutation. The onset of this neurological condition occurs in some men over 50. The most common features are
- ataxia (balance or gait problems)
- an intention tremor (a tremor which occurs during activity- but not at rest)
- and short-term memory loss
For more information on males with the premutation please refer to ‘Fragile X Syndrome:Male Carriers of Fragile X’. Please note that this booklet will be displayed as a pdf file in a new window.
Genetic counselling for carriers
Genetic counselling is very important for all carriers of fragile X, both men and women.Genetic counsellors can give up to date information about how fragile X is passed on, and about the reproductive implications and options.
Support and information for carriers
The Family Support and Information Service provided by Jane and Wendy, our Family Support Workers, is also available to carriers. Details about the various ways in which both members and non-members can access their help and support are listed in our Contact Us page.
In the main, carriers with a fragile X premutation do not display the effects of the syndrome; however, there are a few incidences where children or adults diagnosed with the premutation have shown some effects that would normally be associated with a full mutation. If this is the case in your family or with the person you are working with then please contact Jane and Wendy (see above) for more details.
Carriers may also wish to take part in the Society's Member's Forum where they can contact other family members in order to seek friendship and share knowledge and experiences.
Carrier specific information papers
Our papers containing further information about the various issues that may be of interest to carriers of fragile X are listed below. Whereas the majority of these papers are free to family members of the Society (and carriers can be family members too, at no cost), a small charge is made for non-members to cover our reproduction costs.
- 'Talking about genetic risk to children: more than carrier testing' by Allyn McConkie-Rosell, Gail Spiridigliozzi, Elizabeth Melvin
- 'Prenatal testing for fragile X' by Barbara Carmichael
- 'Preimplantation genetic diagnosis for fragile X carriers' by Lynne Zwink
- 'Identification of the fragile X associated tremor-ataxia syndrome, known as FXTAS, in carriers of the fragile X premutation' by Lynne Zwink
- 'Clinical features of boys with fragile X premutations and intermediate alleles' by Dr Monica Aziz & Dr Jeremy Turk
- 'Male carriers of fragile X ' (booklet) - Reports the findings of the UK study of men who carry a fragile X premutation. By Dr Kim Cornish & Dr Jeremy Turk
To obtain copies of any of the papers listed above please either Contact Us or request them via the Publications Order Form, which contains details of the full range of our information about all aspects of fragile X . Please note that a new window will open for this Publications Oder Form pdf file.
See also
UK Research Reports
Current UK Fragile X Studies
Acknowledgements
The majority of the information on this page has been taken from the 'Carriers : What it means' page as at January 2009 of The National Fragile X Foundation, whose website address is
www.fragilex.org.