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Fragile X syndrome (FXS) is a genetic neurodevelopmental disorder characterized by mild-to-moderate intellectual disability. [1] The average IQ in males with FXS is under 55, while about two thirds of affected females are intellectually disabled.
Fragile X-associated tremor/ataxia syndrome (FXTAS) is a late-onset neurodegenerative disorder most frequently seen in male premutation carriers of Fragile X syndrome (FXS) over the age of 50. [ 4 ] [ 5 ] The main clinical features of FXTAS include problems of movement with cerebellar gait ataxia and action tremor .
These mutations disrupt the 3-dimensional shape of FMRP or prevent the protein from being synthesized, leading to the signs and symptoms of fragile X syndrome. A CGG sequence in the FMR1 gene that is repeated between 55 and 200 times is described as a premutation. Although most individuals with the premutation are intellectually normal, some of ...
The condition is commonly inherited in connection with fragile X syndrome (FXS), which is also the second most common genetic cause of intellectual disability. [1] The condition is also a rare sign of McCune–Albright syndrome. [2] The opposite of macroorchidism is called microorchidism, which is the condition of abnormally small testes.
The first trinucleotide repeat disease to be identified was fragile X syndrome, which has since been mapped to the long arm of the X chromosome. Patients carry from 230 to 4000 CGG repeats in the gene that causes fragile X syndrome, while unaffected individuals have up to 50 repeats and carriers of the disease have 60 to 230 repeats.
Fragile X-associated primary ovarian insufficiency (FXPOI) is the most common genetic cause of premature ovarian failure in women with a normal karyotype 46,XX. [1] The expansion of a CGG repeat in the 5' untranslated region of the FMR1 gene from the normal range of 5-45 repeats to the premutation range of 55-199 CGGs leads to risk of FXPOI for ovary-bearing individuals. [2]
If the errors accumulate relatively quickly, the person might get symptoms beginning in their 30s or 40s and die, typically 10 to 15 years later, becoming a tremendous burden on their family in ...
Sherman theorized that the gene responsible for fragile X syndrome becomes mutated through a two-step process. The first mutation, called the 'premutation', doesn't cause any clinical symptoms. A second mutation was required to convert the 'premutation' into a 'full mutation' capable of causing the clinical symptoms associated with fragile X ...