0
When does a fragile X premutation become a full mutation?
GaleEncyofMedicine
Once the size of the premutation exceeds 230 repeats, it becomes a full mutation and the FMR-1 gene is disabled. Individuals who carry the full mutation may have fragile X syndrome
Wiki User
∙ 13y ago
Add your answer:
Earn +20 pts
How is Fragile X Syndrome Inherited?
Males and females can be carriers, male carriers can only pass on to their daughters, they will be carriers as well have a premutation. Females can pass on to their sons or daughters, they will have the premutation or the full mutation.
What is a X linked carrier homozygous?
An X linked carrier is one who carries a mutation in a gene found on the X sex chromosome. A carrier of the trait doesn't display phenotypic symptoms of the disease or mutation but can transfer the mutation in that gene to their offspring (ex: the carrier of a premutation that when transferred to the offspring via the X chromosome will cause the full mutation associated with that gene). A person could be a homozygous carrier if for instance, she were female (two X chromosomes) and carried the premutation associated with the disease. Some diseases need both alleles of the gene to be mutated. If only one allele is mutated (heterozygote) that person may be a carrier for that mutation and can thus pass on that mutation to their children.
Why are males more likely to have fragile X syndrome?
males have only one copy of the X chromosome. Males who inherit the full mutation are expected to have mental impairment. A female's normal X chromosome may compensate for her chromosome with the fragile X gene mutation
Can you get a disease from fragile x syndromes and how?
The definition of disease is loosely defined as an illness that can potentionally be cured; Cancer is an example of a disease. . Fragile X syndrome: (FXS) is a genetic condition that causes intellectual disability, behavioral and learning challenges and various physical characteristics. Though FXS occurs in both genders, males are more frequently affected than females, and generally with greater severity. FXS is the most common known genetic ("single gene") cause of autism.Many studies have evaluated the FXS-autism link over the past decade. These studies have shown the percentage of children with FXS who have autism varying from 15 to 33 percent. This range may be due to the fact that the diagnostic criteria for autism have varied and the diagnostic tools used have changed. Since many children with FXS are interested in social interactions, they may not meet the diagnostic criteria for autism, even as they exhibit autistic-like features such as poor eye contact, shyness, social anxiety, hand-flapping and sensory issues. Autism is much more common in boys with FXS than in girls with FXS. Carriers: Approximately 1 in 250 females and 1 in 800 males carry the FMR1 premutation. They are thus "carriers" of the premutation. Premutations are defined as having 55-200 CGG repeats and can occur in both males and females. When a father passes the premutation on to his daughters, it usually does not expand to a full mutation. A man never passes the fragile X gene to his sons, since he passes only his Y chromosome to them, which does not contain a fragile X gene. A female with the FMR1 premutation will often pass on a larger version of the mutation to her children (more on this point below). She also has a 50 percent chance of passing on her normal X chromosome in each pregnancy, since usually only one of her X chromosomes has the FMR1 mutation. The chance of the premutation expanding to a full mutation is related to the size of the mother's premutation. The larger the mother's CGG repeat number, the higher the chance that it will expand to a full mutation if it is passed on. Fragile X Associated Disorders: FXTAS: is caused by a change or mutation in a gene called the FMR1 gene. All individuals with FXTAS have what is called an FMR1 premutation. Men with FXTAS inherited this genetic change from their mother, women with FXTAS can inherit it from their mother or father. FXTAS- is an "adult onset" neurodegenerative disorder, occurring more commonly in males than females. Onset is usually over 50 years of age, and most individuals had no related medical, developmental or neurological problems prior to the appearance of FXTAS symptoms. Females comprise only a small part of the FXTAS population, and their symptoms tend to be less severe. Symptoms of FXTAS include: Ataxia (balance problems). Intention tremors (during intentional movement such as pouring, writing, etc,). Memory loss (usually short-term). Mood instability, irritability, personality change, psychiatric symptoms. Parkinson's symptoms (many individuals will be misdiagnosed with Parkinson's Disease" prior to diagnosis of FXTAS). Dementia (many individuals will be misdiagnosed with Alzheimer's disease prior to diagnosis FXTAS). Cognitive decline (loss of math, reading, and verbal comprehension skills). FXTAS progresses at varying rates in different individuals. FXPOI: or fragile X-associated primary ovarian insufficiency, is one of three known Fragile X-associated Disorders (FXD). All the FXD are caused by changes in the FMR1 Gene. FXPOI is a condition in which the ovaries are not functioning at full capacity in an FMR1 premutation carrier. Common symptoms of FXPOI include absent or irregular periods, symptoms of menopause such as hot flashes, etc, early menopause and infertility. By definition, all women who have FXPOI have an FMR1 premutation. If you are experiencing FXPOI symptoms and haven't been tested you should arrange with your physician to have FMR1 genetic testing. If you have already been tested and are a confirmed FMR1 premutation carrier, you should alert your physician to the risk of FXPOI in carriers (some physicians might not be aware of this condition). All female FMR1 carriers should keep a log of their menstrual cycles and note any unusual patterns, missed cycles, abnormally long cycles (more than 35 days) or short cycles (less than 21 days). Also note any other physical changes such as hot flashes, insomnia, vaginal dryness and/or decreased libido, increased anxiety, etc. If you are concerned that you might have FXPOI, talk to your physician about having your FSH, a hormone that reflects ovarian function, measured. FSH levels increase as you approach menopause or if your ovaries are not functioning properly for your age. FXPOI occurs in about 20-25 percent of adult female FMR1 premutation carriers. It has also been reported in teenagers who are carriers, though it is less common in that population. To answer your question- Fragile X is not contagious, and you cannot get a disease from an individual diagnosed with fragile X syndrome. However- premutation carriers are at risk of developing a fragile X associated disorder.
Fragile X syndrome affects only females?
No, Fragile X is on the X chromosome. Females have 2 X chromosomes and Males have an X and a Y Chromosome. Therefore, both males and females can have Fragile X (they can have the full mutation or be carriers). Males are usually more severly affected because they have only one X Chromosome.
What are the chances of someone with Fragile X Syndrome passing it on to someone else?
Males who are carriers will pass on the gene to all of their daughters, they will be FX carriers. Females who have the premutation (50-200 CGG repeats) or full-mutation (over 200 CGG repeats) have a 50/50 chance of passing it on with each pregnancy. Now just because they pass it on doesn't mean the child will be affected (especially when it comes to girls, since girls have 2 X chromosomes, the other X may produce enough protein.)
What are the possible genotypes of parents in fragile x syndrome?
A/X X/A NIKKI SMITH **** Less than 1% of Fragile X Syndrome cases are a result of deletion, neither parent is a carrier. If a father is the carrier/full mutation, XY, he will pass the mutated gene to all of his daughters, all of his daughters will be carriers. If the mother is the carrier/full mutation, xX, with each pregnancy she has the possiblity of passing on fragile X as a pre-mutation (carriers) or full-Mutation to every child (male/female).
What is the full quote from The Last Song that starts with Love is fragile and we're not always its best caretakers?
"Love is fragile and we're not always its best caretakers. We just muddle through and do the best we can, hoping this fragile thing survives against all odds." - The Last Song
How did the expression love is a fragile flower opening to the warmth of spring come about?
a heart opening full of love .
A mutation occurs in the sex cells of a full-grown zebra. The mutation affects the genes responsible for producing blood proteins. What will most likely happen to the zebra?
The zebra will have offspring who cannot produce blood proteins.
What type of mutation causes Edwards' syndrome?
An extra copy of Chromosome 18
Why does my FuzCub from a full generation of black eyes on CreatureBreeder have blue eyes?
Possibly a genetic mishap or a mutation ( not like the ones from X-men)
