What type of mutation is fragile x

A few individuals with a premutation have subtle intellectual or behavioral symptoms, such as learning difficulties or social anxiety. The difficulties are usually not socially debilitating, and these individuals may still marry and have children.

Other neurologic findings include short-term memory loss, executive function deficits, cognitive decline, parkinsonism, peripheral neuropathy, lower-limb proximal muscle weakness, and autonomic dysfunction. The degree to which clinical symptoms of fragile X are present penetrance is age related; symptoms are seen in 17 percent of males aged years, in 38 percent of males aged years, in 47 percent of males aged years, and in 75 percent or males aged 80 years or older.

Some female premutation carriers may also develop tremor and ataxia. Females who have a premutation usually are unaffected, but may be at risk for premature ovarian failure and FXTAS. Premature ovarian failure POF is defined as cessation of menses before age 40 years, has been observed in carriers of premutation alleles. A review by Sherman concluded that the risk for POF was 21 percent in premutation carriers compared to a 1 percent for the general population.

There are very few outward signs of fragile X syndrome in babies, but one is a tendency to have a large head circumference. An experienced geneticist may note subtle differences in facial characteristics. Intellectual disability is the hallmark of this condition and, in females, this may be the only sign of the problem. A specific genetic test polymerase chain reaction [PCR] can now be performed to diagnose fragile X syndrome.

This test looks for an expanded mutation called a triplet repeat in the FMR1 gene. There is no specific treatment available for fragile X syndrome. Supportive therapy for children who have fragile X syndrome includes:. Special education and anticipatory management including avoidance of excessive stimulation to decrease behavioral problems.

Medication to manage behavioral issues, although no specific medication has been shown to be beneficial. Vision, hearing, connective tissue problems, and heart problems when present are treated in the usual manner. Premutation carriers of an FMR1 gene mutation can have no apparent signs of a Fragile X disorder, and may or may not develop FXTAS pronounced: FAKS-taz , which usually occurs in male premutation carriers after age 50, with symptoms — including balance, tremor, and memory problems — worsening with age.

Premutation carriers of an FMR1 gene mutation can have no apparent signs of a Fragile X disorder, and may or may not develop FXPOI pronounced: FAKS-poi , which usually occurs in female premutation carriers after age 40, and refers to a spectrum of impaired ovarian functions that can include infertility and early menopause. Fragile X-associated disorders include a wide range of physical, intellectual, and behavioral symptoms that can affect family members in many different ways.

These conditions are passed down in families through expansions of the FMR1 gene. We start with some background on genetics and chromosomes …. Who should be tested, lab tests for Fragile X including testing costs and reporting time, and other tests for children with developmental delay.

Fragile X Info Series flyers are designed to be easily printable on home and office printers. Whatever the cause, they are meant to be informative and shareable. Fragile X What is Fragile X Syndrome? Males have only one X chromosome which is inherited from the mother.

They receive a Y chromosome from the father. Females inherit two X chromosomes, one from each parent. This gene, called FMR1, was discovered in by Drs. It causes almost all cases of Fragile X syndrome. The FMR1 gene is located on the long arm of the X chromosome.

At the start of this gene lies a region of DNA which varies in length from one person to another. In some people, however, this stretch of DNA is somewhat longer; this gene change is a premutation. This stretch of DNA is prone to further expansion when it is passed from a woman to her children. When the stretch of DNA expands beyond a certain length, the gene is switched off and does not produce the protein that it normally makes.

This gene change is called a full mutation. A male who inherits a full mutation exhibits Fragile X syndrome because his only X chromosome contains the mutated gene.