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

Year 2026, Volume: 39 Issue: 1, 1 - 5, 28.01.2026

Ceren Alavanda , Kayıhan Uluç , Pinar Kahraman Dilşad Türkdoğan , Ahmet Arman

https://doi.org/10.5472/marumj.1872686

https://izlik.org/JA62TT23PK

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

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