Fragile X syndrome
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| Fragile X syndrome | |
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| Location of FMR1 gene | |
| ICD-10 | Q99.2 |
| ICD-9 | 759.83 |
| OMIM | 309550 |
| DiseasesDB | 4973 |
| MeSH | D005600 |
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Fragile X syndrome Microchapters |
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Fragile X syndrome On the Web |
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American Roentgen Ray Society Images of Fragile X syndrome |
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
Synonyms and keywords:: Martin-bell syndrome; marker X syndrome, escalante's syndrome
Overview
Fragile x syndrome is the leading inherited cause of intellectual disorder and autism spectrum disorder with severe behavioral abnormalities . It is an X linked disorder, affecting both males and females. It is a genetic disease caused by CGG trinucleotide expansion (>200 CGG repeats).
Historical Perspective
Fragile X syndrome was described first by Martin and Bell in 1943. [1]
Classification
Pathophysiology
Fragile x syndrome has an x-linked dominant inheritance. It is caused by an expansion of CGG trinucleotide repeat within FMR1 gene on X chromosome. Due to high number of CGG repeats (>200), this leads to methylation of part of gene on X chromosome that codes for Fragile X Mental retardation protein (FMRP), which is required for proper development of connections between neurons. [2]
Causes
Fragile x Syndrome is a genetic disease which is caused by mutation in the Fragile x Mental Retardation 1(FMR1) gene in X chromosome. Generally, these mutation (>200 repeats of CGG) occurs at in the 5' untranslated region of FMR1.[3] In around 2% of cases, Fragile X syndrome can occur as a result of point mutation in FMR1 gene.[4]
Differentiating Fragile X syndrome from other Diseases
Fragile X syndrome must be differentiated from Autism Spectrum Disorder, Attention deficit hyperactivity disorder (ADHD), Fragile XE syndrome (FRAXE), Klinefelter syndrome and Prader-Willi syndrome (PWS).[5]
Epidemiology and Demographics
The prevalence of Fragile X syndrome is approximately 1 in 5000 men and 1 in 4000-6000 women worldwide, determined by molecular assays. [6]
Risk Factors
Screening
Natural History, Complications and Prognosis
Diagnosis
History and Symptoms | Physical Examination | Laboratory Findings | Other Diagnostic Studies
Treatment
Medical Therapy | Primary Prevention | Secondary Prevention | Cost Effectiveness of Therapy | Future or Investigational Therapies
Case Studies
External links
Template:Pervasive developmental disorders Template:Chromosomal abnormalities
- ↑ Martin JP, Bell J. A pedigree of mental defect showing sex- linkage. J Neurol Psychiatry. 1943; 6(3-4): 154–7.
- ↑ 1. fragile X syndrome - Genetics Home Reference [Internet]. 2016 [cited 2021 Jul 15]. Available from: https://web.archive.org/web/20161009162713/https://ghr.nlm.nih.gov/condition/fragile-x-syndrome
- ↑ Santoro MR, Bray SM, Warren ST (2012). "Molecular mechanisms of fragile X syndrome: a twenty-year perspective". Annu Rev Pathol. 7: 219–45. doi:10.1146/annurev-pathol-011811-132457. PMID 22017584.
- ↑ Peprah E (2012). "Fragile X syndrome: the FMR1 CGG repeat distribution among world populations". Ann Hum Genet. 76 (2): 178–91. doi:10.1111/j.1469-1809.2011.00694.x. PMC 3288311. PMID 22188182.
- ↑ Wiesner GL, Cassidy SB, Grimes SJ, Matthews AL, Acheson LS (2004). "Clinical consult: developmental delay/fragile X syndrome". Prim Care. 31 (3): 621–5, x. doi:10.1016/j.pop.2004.04.008. PMID 15331251.
- ↑ Coffee B, Keith K, Albizua I, Malone T, Mowrey J, Sherman SL; et al. (2009). "Incidence of fragile X syndrome by newborn screening for methylated FMR1 DNA". Am J Hum Genet. 85 (4): 503–14. doi:10.1016/j.ajhg.2009.09.007. PMC 2756550. PMID 19804849.