DNA Replication Mechanisms in Genetic Disorders

Faithful replication of the genome is essential for development, tissue homeostasis and prevention of malignancy. Key steps in eukaryotic DNA replication include the licensing of replication origins, assembly of the replisome and activation of the CMG helicase complex to unwind the double helix. Mutations affecting any component of this machinery can give rise to a spectrum of genetic disorders characterised by growth retardation, developmental anomalies and immune dysfunction. In syndromes such as Meier-Gorlin, biallelic variants in genes encoding origin-licensing factors impair the recruitment of the minichromosome maintenance complex, limiting replication initiation and cell proliferation. Defects in replisome components or accessory factors generate replication stress, accumulate single-stranded DNA gaps and trigger checkpoint activation, which can manifest clinically as craniosynostosis, microcephaly or bone marrow failure. Conversely, hypomorphic mutations in polymerases alter genome stability and predispose to tumour development. Research in this field not only elucidates fundamental principles of origin firing, fork progression and post-replicative repair but also guides the development of targeted therapies, for example PARP inhibitors in contexts of polymerase dysfunction. A detailed understanding of the interplay between replication dynamics and cell cycle control is critical to improving diagnostics, counselling and treatment in affected individuals worldwide.

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DNA Replication Mechanisms in Genetic Disorders publication trend

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Technical terms

Origin licensing: The process by which origin recognition complex proteins, CDC6 and CDT1 load MCM helicase onto DNA during G1 phase to prepare replication start sites.

Replisome: The multi-protein machinery, including DNA polymerases, helicases and accessory factors, responsible for unwinding DNA and synthesising new strands during S phase.

CMG helicase complex: The active helicase composed of CDC45, MCM2-7 and GINS that unwinds DNA at replication forks.

Replication stress: A state of slowed or stalled fork progression leading to accumulation of single-stranded DNA and activation of ATR-mediated checkpoint signalling.

Post-replicative repair: Mechanisms, such as template switching and gap filling, that resolve lesions encountered after the replication fork has passed, preserving genome integrity.

References

1. The loss of DNA polymerase epsilon accessory subunits POLE3–POLE4 leads to BRCA1-independent PARP inhibitor sensitivity. Nucleic Acids Research (2024).
2. Polε Instability Drives Replication Stress, Abnormal Development, and Tumorigenesis. Molecular Cell (2018).
3. Deficiency in Origin Licensing Proteins Impairs Cilia Formation: Implications for the Aetiology of Meier-Gorlin Syndrome. PLOS Genetics (2013).
4. Biallelic GINS2 variant p.(Arg114Leu) causes Meier-Gorlin syndrome with craniosynostosis. Journal of Medical Genetics (2021).
5. The expanding genetic and clinical landscape associated with Meier-Gorlin syndrome. European Journal of Human Genetics (2023).