Fragile X Syndrome

Introduction

X-Linked recessive (affected father)

Fragile X Syndrome (Mental Retardation, X-linked, associated with marXq28, X-linked mental retardation and macroorchidism, Marker X syndrome, Martin-Bell syndrome).

Most cases result from the unstable expansion of a CGG repeat in the FMR1 gene and abnormal methylation, leading to repression of FMR1 transcription and subsequent decreased protein levels in the brain.

International Classification of Diseases code (Q99.2 Fragile X chromosome Fragile X syndrome).

Undergraduate Science students project 2011 Fragile X Syndrome.

Some Recent Findings

Genetic Counseling and Testing for FMR1 Gene Mutations: Practice Guidelines of the National Society of Genetic Counselors "Fragile X syndrome (FXS) is one of several clinical disorders associated with mutations in the X-linked Fragile X Mental Retardation-1 (FMR1) gene. With evolving knowledge about the phenotypic consequences of FMR1 transcription and translation, sharp clinical distinctions between pre- and full mutations have become more fluid. The complexity of the issues surrounding genetic testing and management of FMR1-associated disorders has increased; and several aspects of genetic counseling for FMR1 mutations remain challenging, including risk assessment for intermediate alleles and the widely variable clinical prognosis for females with full mutations. FMR1 mutation testing is increasingly being offered to women without known risk factors, and newborn screening for FXS is underway in research-based pilot studies. Each diagnosis of an FMR1 mutation has far-reaching clinical and reproductive implications for the extended family. The interest in large-scale population screening is likely to increase due to patient demand and awareness, and as targeted pharmaceutical treatments for FXS become available over the next decade. Given these developments and the likelihood of more widespread screening, genetic counselors across a variety of healthcare settings will increasingly be called upon to address complex diagnostic, psychosocial, and management issues related to FMR1 gene mutations. The following guidelines are intended to assist genetic counselors in providing accurate risk assessment and appropriate educational and supportive counseling for individuals with positive test results and families affected by FMR1-associated disorders."

Recent References | References | PubMed

International Classification of Diseases

The International Classification of Diseases (ICD) World Health Organization's classification used worldwide as the standard diagnostic tool for epidemiology, health management and clinical purposes. This includes the analysis of the general health situation of population groups. It is used to monitor the incidence and prevalence of diseases and other health problems. Within this classification "congenital malformations, deformations and chromosomal abnormalities" are (Q00-Q99) but excludes "inborn errors of metabolism" (E70-E90).

Q99 Other chromosome abnormalities, not elsewhere classified

• Q99.2 Fragile X chromosome Fragile X syndrome

ICD-10

Fragile X-associated Tremor

(Ataxia Syndrome) A mainly male adult-onset condition that causes tremor and affects balance and memory in some "carriers" of the Fragile X gene. Because of the adult onset, this can be mistaken for a range of other neurological disorders including Parkinson's and Alzheimer's disease.

References

NCBI Bookshelf

• Modern Genetic Analysis Griffiths, Anthony J.F.; Gelbart, William M.; Miller, Jeffrey H.; Lewontin, Richard C. New York: W. H. Freeman & Co.; c1999.
• Introduction to Genetic Analysis 7th ed. Griffiths, Anthony J.F.; Miller, Jeffrey H.; Suzuki, David T.; Lewontin, Richard C.; Gelbart, William M. New York: W. H. Freeman & Co.; c1999.
• Clinical Methods 3rd ed. Walker, H.K.; Hall, W.D.; Hurst, J.W.; editors Stoneham (MA): Butterworth Publishers; c1990 Table - Recognizable Genetic Conditions

Reviews

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Articles

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Associated Neurological

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Books

Note: books are listed for educational and information purposes only and does not suggest a commercial product endorsement.

OMIM

• 300624 FRAGILE X MENTAL RETARDATION SYNDROME

Search PubMed

Search PubMed Now: Fragile X Syndrome

External Links

External Links Notice - The dynamic nature of the internet may mean that some of these listed links may no longer function. If the link no longer works search the web with the link text or name. Links to any external commercial sites are provided for information purposes only and should never be considered an endorsement. UNSW Embryology is provided as an educational resource with no clinical information or commercial affiliation.

• USA - National Fragile X Foundation
• Australia - Fragile X Association of Australia

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Cite this page: Hill, M.A. (2024, April 23) Embryology Fragile X Syndrome. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Fragile_X_Syndrome

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© Dr Mark Hill 2024, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G