Journal of Rafsanjan University of Medical Sciences
Volume 25, Issue 2 (7-2026)
JRUMS 2026, 25(2): 147-174 |
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Ethics code: IR.YAZD.REC.1402.050
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Heidari M M, Madani Manshadi S A, Jafari Nejad Bidgoli E, Khatami M, Ordooei M. Identification of Novel Variants in Mitochondrial tRNALys and tRNAGly Genes Associated with Congenital Hypothyroidism based on Molecular Evidence and Bioinformatic Analysis:
A Case-Control Study. JRUMS 2026; 25 (2) :147-174
URL: http://journal.rums.ac.ir/article-1-7845-en.html
URL: http://journal.rums.ac.ir/article-1-7845-en.html
Mohammad Mehdi Heidari 
, Seyed Ali Madani Manshadi , Elaheh Jafari Nejad Bidgoli , Mehri Khatami , Mahtab Ordooei
, Seyed Ali Madani Manshadi , Elaheh Jafari Nejad Bidgoli , Mehri Khatami , Mahtab Ordooei
Yazd University
Abstract: (22 Views)
Background and Objectives: Although several pathogenic factors underlying congenital hypothyroidism have been identified, the contribution of mitochondrial genome (mtDNA) variants remains incompletely understood. This study aimed to identify and functionally characterize mitochondrial variants in the tRNAGly and tRNALys genes in patients with congenital hypothyroidism.
Materials and Methods: In this case–control study, 75 patients aged 3–11 years and an equal number of healthy individuals as the control group were enrolled. Following DNA extraction from peripheral blood samples, the tRNAGly and tRNALys gene regions were amplified using touchdown PCR, and the variants were screened by single-strand conformational polymorphism (SSCP) analysis. The variants identified were confirmed by Sanger sequencing and subsequently analyzed using a panel of advanced bioinformatics tools to evaluate their effects on tRNA secondary structure, molecular stability, and predicted pathogenicity.
Results: Two variants in the tRNAGly gene, a missense mutation (p.Val254Ile) in the MT-CO3 gene encoding cytochrome c oxidase subunit III, and two heteroplasmic variants in the tRNALys gene (8335A>G and 8348A>G) were identified. The 10011A>G variant reduces tRNAGly secondary structure stability by disrupting hydrogen bonding, while 10034T>C, located in a critical variable loop region, may lead to codon misrecognition. The p.Val254Ile variant in MT-CO3 was predicted to be pathogenic by all in silico tools. The tRNALys variants are located within a region essential for ribosomal binding.
Conclusion: This study confirms the presence of diverse mitochondrial variants in patients and supports a potential role of mitochondrial dysfunction in the pathogenesis of congenital hypothyroidism.
Keywords: Congenital hypothyroidism, Mitochondrial genome, Bioinformatics, tRNALys, tRNAGly, MT-CO3
Funding: This study was funded by Yazd University, Yazd, Iran.
Conflict of interest: None declared.
Ethical considerations: The Ethics Committee of Yazd University approved the study (IR.YAZD.REC.1402.050).
Authors’ contributions:
- Conceptualization: Mohammad Mehdi Heidari
- Methodology: Seyed Ali Madani Manshadi, Elaheh Jafari Nejad Bidgoli, Mahtab Ordooei
- Data collection: Seyed Ali Madani Manshadi, Elaheh Jafari Nejad Bidgoli, Mahtab Ordooei
- Formal analysis: Mohammad Mehdi Heidari, Mehri Khatami
- Supervision: Mohammad Mehdi Heidari, Mehri Khatami
- Project administration: Mohammad Mehdi Heidari
- Writing - original draft: Mohammad Mehdi Heidari, Elaheh Jafari Nejad Bidgoli, Mehri Khatami
- Writing - review & editing: Mohammad Mehdi Heidari, Mehri Khatami
Materials and Methods: In this case–control study, 75 patients aged 3–11 years and an equal number of healthy individuals as the control group were enrolled. Following DNA extraction from peripheral blood samples, the tRNAGly and tRNALys gene regions were amplified using touchdown PCR, and the variants were screened by single-strand conformational polymorphism (SSCP) analysis. The variants identified were confirmed by Sanger sequencing and subsequently analyzed using a panel of advanced bioinformatics tools to evaluate their effects on tRNA secondary structure, molecular stability, and predicted pathogenicity.
Results: Two variants in the tRNAGly gene, a missense mutation (p.Val254Ile) in the MT-CO3 gene encoding cytochrome c oxidase subunit III, and two heteroplasmic variants in the tRNALys gene (8335A>G and 8348A>G) were identified. The 10011A>G variant reduces tRNAGly secondary structure stability by disrupting hydrogen bonding, while 10034T>C, located in a critical variable loop region, may lead to codon misrecognition. The p.Val254Ile variant in MT-CO3 was predicted to be pathogenic by all in silico tools. The tRNALys variants are located within a region essential for ribosomal binding.
Conclusion: This study confirms the presence of diverse mitochondrial variants in patients and supports a potential role of mitochondrial dysfunction in the pathogenesis of congenital hypothyroidism.
Keywords: Congenital hypothyroidism, Mitochondrial genome, Bioinformatics, tRNALys, tRNAGly, MT-CO3
Funding: This study was funded by Yazd University, Yazd, Iran.
Conflict of interest: None declared.
Ethical considerations: The Ethics Committee of Yazd University approved the study (IR.YAZD.REC.1402.050).
Authors’ contributions:
- Conceptualization: Mohammad Mehdi Heidari
- Methodology: Seyed Ali Madani Manshadi, Elaheh Jafari Nejad Bidgoli, Mahtab Ordooei
- Data collection: Seyed Ali Madani Manshadi, Elaheh Jafari Nejad Bidgoli, Mahtab Ordooei
- Formal analysis: Mohammad Mehdi Heidari, Mehri Khatami
- Supervision: Mohammad Mehdi Heidari, Mehri Khatami
- Project administration: Mohammad Mehdi Heidari
- Writing - original draft: Mohammad Mehdi Heidari, Elaheh Jafari Nejad Bidgoli, Mehri Khatami
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Citation: Heidari MM, Madani Manshadi SA, Jafari Nejad Bidgoli E, Khatami M, Ordooei M. Identification of Novel Variants in Mitochondrial tRNALys and tRNAGly Genes Associated with Congenital Hypothyroidism Based on Molecular Evidence and Bioinformatic Analysis: A Case-Control Study. J Rafsanjan Univ Med Sci 2026; 25 (2): 147-74. doi: 10.66224/jrums.25.2.147. [Farsi].
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Type of Study: Research |
Subject:
Pediatrics
Received: 2025/09/25 | Accepted: 2026/06/10 | Published: 2026/07/28
Received: 2025/09/25 | Accepted: 2026/06/10 | Published: 2026/07/28
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