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Fragile X Syndrome

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Fragile X Syndrome (FXS) is an X-linked dominant disorder that results in a variety of developmental problems, and is a common cause of inherited intellectual disability.

Fragile X Syndrome is caused by a CGG trinucleotide repeat, in the FMR1 gene, resulting in hypermethylation and reduced gene expression.

While both sexes are affected, the disease is both more prevalent and more severe in boys. Clinical findings classically includedevelopmental delay , which is associated with autism spectrum disorder and IQ decreases.

Other physical features include long facies, large everted ears, and macroorchidism (large testes in boys). Cardiac complications can include mitral valve prolapse.

Find Fragile X Syndrome and other Chromosomal Abnormalities among Pixorize's visual mnemonics for the USMLE Step 1 Exam.