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Fragile X

Overview of the Fragile X Blood Test

The Fragile X blood test is used to diagnose Fragile X syndrome, a genetic condition recognized as the most common inherited cause of intellectual disability and autism.

What the Test Measures

This test analyzes the number of CGG repeats in a specific DNA sequence located on the X chromosome, known as the Fragile X Mental Retardation 1 (FMR1) gene.

Cause of Fragile X Syndrome

Fragile X syndrome results from a mutation in the FMR1 gene, which affects the production of a protein called Fragile X Mental Retardation Protein (FMRP). Abnormal levels or absence of FMRP impact brain development and function.

Severity and Symptoms

The severity of the condition is linked to the size of the CGG repeat expansion:

Smaller expansions may result in mild intellectual disability

Larger expansions can cause more severe intellectual impairment, along with symptoms such as autism, ADHD, and behavioral or emotional issues

How the Test is Performed

A small blood sample is collected and analyzed in a laboratory to measure the repeat expansion in the FMR1 gene.

Interpretation of Results

A positive result indicates the presence of Fragile X syndrome

A negative result means the individual does not have the condition

Clinical Use

The Fragile X test is a reliable diagnostic tool often used alongside other assessments to confirm the diagnosis and guide treatment planning.