Comparison of Two Different PCR-based Methods for Detection of GAA Expansions in Frataxin Gene

  • Mona ENTEZA­M Dept. of Medical Genetics, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran
  • Akbar AMIRFIROOZI Dept. of Medical Genetics, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran
  • Mansoureh TOGHA Iranian Center of Neurological Research, Neuroscience Institute, Tehran University of Medical Sciences, Tehran, Iran Dept. of Neurology, Sina Hospital, Tehran University of Medical Sciences, Tehran, Iran
  • Mohammad KERAMATIPOUR Dept. of Medical Genetics, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran
Triplet repeat primed-PCR, Long-PCR, GAA trinucleotide repeat, Friedreich’s ataxia, Frataxin (FXN) gene


Background: Expansion of GAA trinucleotide repeats is the molecular basis of Friedreich’s ataxia (FRDA). Precise detection of the GAA expansion repeat in frataxin gene has always been a challenge. Different molecular methods have been suggested for detection of GAA expansion, including; short-PCR, long-PCR, Triplet repeat primed-PCR (TP-PCR) and southern blotting. The aim of study was to evaluate two PCR-based methods, TP-PCR and long-PCR, and to explore the use of TP-PCR accompanying with long-PCR for accurate genotyping of FRDA patients.

Methods: Blood samples were collected from six Iranian patients suspected to FRDA, who referred to the Department of Medical Genetics at Tehran University of Medical Sciences during the year 2014. For one of these patients’ four asymptomatic members of the family were also recruited for the analysis. DNA extraction was performed by two different methods. TP-PCR and long-PCR were carried out in all samples. The type of this study is assessment / investigation of methods.

Results: Using a combination of the above methods, the genotypes of all samples were confirmed as five homozygous mutants (expanded GAA repeats), two heterozygous and three homozygous normal (normal repeat size). The results obtained by TP-PCR are consistent with long-PCR results.

Conclusion: The presence or absence of expanded alleles can be identified correctly by TP-PCR. Performing long-PCR and Fluorescent-long-PCR enables accurate genotyping in all samples. This approach is highly reliable. It could be successfully used for detection of GAA expansion repeats.



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How to Cite
ENTEZA­MM, AMIRFIROOZI A, TOGHA M, KERAMATIPOUR M. Comparison of Two Different PCR-based Methods for Detection of GAA Expansions in Frataxin Gene. Iran J Public Health. 46(2):222-228.
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