fragile X syndrome

Epidemiology

• fragile X syndrome is the 2nd most common genetic form of mental retardation (after Down's syndrome)
• occurs in about 1/2000 births

Genetics

• associated with folate-sensitive fragile site on the long arm of the X chromosome
• associated with defects in FMR1
• the defect in most fragile X syndrome patients results from an amplification of a CGG repeat region which is directly in front of the coding region
• > 200 CGC repeats in fragile X syndrome

Clinical manifestations

• moderate to severe mental retardation
• testicular enlargement
• large ears
• prominent jaw
• high-pitched, jocular speech

Laboratory

• Fragile X syndrome genotyping

More general terms

• X-linked disease
• trinucleotide repeat expansion disease

More specific terms

• fragile X syndrome FRAXA site
• fragile X syndrome FRAXE site
• fragile X tremor/ataxia syndrome (FXTAS)

Additional terms

• Fragile X syndrome genotyping

Database

• OMIM: https://mirror.omim.org/entry/300624