Fragile X syndrome
Fragile X syndrome (FXS) is a genetic syndrome that causes a range of intellectual disabilities as well as unusual physical and behavioural characteristics. Males and females can have FXS but it is more common, and often more serious, in males.[1] It is one of the most common causes of autism and intellectual disability among boys.[2][3] Individuals with this condition lack an important gene product.[1]
| Fragile X syndrome | |
|---|---|
| Classification and external resources | |
 Location of FMR1 gene | |
| ICD-10 | Q99.2 |
| ICD-9 | 759.83 |
| OMIM | 300624 |
| DiseasesDB | 4973 |
| MedlinePlus | 001668 |
| eMedicine | ped/800 |
| MeSH | D005600 |
Technical account
Fragile X syndrome occurs as a result of a mutation of the FMR1 gene on the X chromosome. This causes an increase an increase in the number of CGG repeats in the 5' untranslated region of FMR1.[4]
In unaffected individuals, the FMR1 gene contains 5–44 repeats of the CGG codon, most commonly 29 or 30 repeats.[4][5] Between 45 and 54 repeats is considered a "grey zone". Between 55 and 200 repeats in length is described as a premutation allele. Individuals with fragile X syndrome have a full mutation of the FMR1 allele, with over 200 repeats of the CGG codon.[2][5][6]
In these individuals with a repeat expansion greater than 200, there is methylation of the CGG repeat expansion and FMR1 promoter. This silences the FMR1 gene, and its end-product is not made.
Fragile X Syndrome Media
Prominent characteristics of the syndrome include an elongated face and large or protruding ears.
References
- ↑ 1.0 1.1 CDC (2022-06-03). "What is Fragile X Syndrome (FXS)? | CDC". Centers for Disease Control and Prevention. Retrieved 2023-01-11.
- ↑ 2.0 2.1 Lua error in Module:Citation/CS1/Identifiers at line 630: attempt to index field 'known_free_doi_registrants_t' (a nil value).
- ↑ Lua error in Module:Citation/CS1/Identifiers at line 630: attempt to index field 'known_free_doi_registrants_t' (a nil value).
- ↑ 4.0 4.1 Santoro M.R. et al 2012. Molecular mechanisms of Fragile X Syndrome: a twenty-year perspective. Annu. Rev. Pathol. Mech. Dis. 7: 219–45. [1] Archived 2016-05-23 at the Wayback Machine
- ↑ 5.0 5.1 Lua error in Module:Citation/CS1/Identifiers at line 630: attempt to index field 'known_free_doi_registrants_t' (a nil value).
- ↑ Lua error in Module:Citation/CS1/Identifiers at line 630: attempt to index field 'known_free_doi_registrants_t' (a nil value).