Agarose-based long-range polymerase chain reaction assay for genotyping Turkish patients with Friedreich’s ataxia

Abstract

Objective: An agarose-based long-range polymerase chain reaction (PCR) assay was performed on patients with a preliminary diagnosis of Friedreich’s ataxia (FA). It aimed to determine the repeat number in intron 1 of the FXN gene and to investigate the genotype-phenotype correlation. Patients and Methods: Nineteen cases participated in the study. Long-range PCR was performed under appropriate conditions using two custom-designed primer pairs (F1-R1 and F2-R2). The PCR products were run on an agarose gel, and guanine-adenine-adenine (GAA) repeat numbers were determined. Results: Biallelic GAA repeat expansions were detected in 6 patients. Four patients had typical FA. One had late-onset FA (LOFA). Another had very late-onset FA (VLOFA). All patients diagnosed with FA had ataxia and areflexia. The detected repeat numbers were approximately 190-1120 for F1-R1 and 170-1100 for F2-R2. The patient with LOFA had 190/1000 GAA repeats. The VLOFA patient had 290/290 GAA repeats. Conclusion: An earlier clinical onset correlated with higher GAA repeats. An agarose-based long-range PCR assay is a quick, low-cost, and effective way to determine GAA repeats. This study shows it can diagnose the disease and identify carriers.

Keywords

• FA
• Long-range PCR
• FXN
• GAA repeats
• agarose-based

References

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