Friedreich Ataxia Repeat Expansion Analysis

Clinical Use

Use

Friedreich Ataxia Repeat Expansion Analysis seeks to determine the number of GAA repeats in intron 1 of the FXN gene. The condition is a progressive form of ataxia, which leads to symptoms such as muscle weakness, spasticity, dysarthria, and an increased risk for diseases like cardiomyopathy and diabetes. Most patients experience symptoms before age 25, although a subset may present later. The analysis identifies variants linked with Friedreich ataxia, notably the pathogenic expansion of GAA trinucleotide repeats, which occurs in nearly all affected individuals. Testing is especially vital for symptomatic patients, presymptomatic individuals with family histories, and those pursuing pregnancy after confirming a familial risk. Understanding the mutation helps in planning for potential carriers and affected pregnancies.

Special Instructions

This test is particularly useful for patients who may have relatives diagnosed with Friedreich's Ataxia or are considering pregnancy while being aware of the family history. Collecting blood samples should be done with care, especially regarding the shipping method to ensure the viability of specimens. Follow instructions for the appropriate handling of blood samples, DNA, and skin biopsies to preclude contamination and degradation of the specimens.

Limitations

Detecting normal alleles and most expanded alleles is well within the capability of this analysis, although extremely large GAA expansions may necessitate confirmation through Southern blotting. Size ranges of detected alleles will be approximations, subject to modification based on evolving scientific understanding of these trinucleotide repeats. Consequently, care must be taken in interpreting results, especially with borderline cases or atypical repeat sizes. Due to technical constraints, results do not provide absolute sizes for any repeats, and ongoing research may influence these interpretations.

Test Details

FDA Approved