PRIM1 deficiency causes a distinctive primordial dwarfism syndrome

Area of Science:

• Genetics
• Molecular Biology
• Human Disease Genetics

Background:

• DNA replication is essential for cell division and organismal growth.
• Components of the DNA replisome, the complex machinery for DNA replication, are increasingly linked to human pathologies.
• The catalytic subunit of DNA primase, encoded by PRIM1, plays a critical role in initiating DNA replication.

Purpose of the Study:

• To identify novel disease-associated genes within the DNA replication machinery.
• To investigate the role of PRIM1 mutations in human disease.
• To characterize the cellular and phenotypic consequences of PRIM1 deficiency.

Main Methods:

• Variant classification agnostic approach to identify genetic mutations.
• Analysis of PRIM1 gene mutations in affected individuals.
• Assessment of PRIM1 protein levels in patient-derived cells.
• Evaluation of DNA replication dynamics, including fork asymmetry, interorigin distances, and S-phase duration.
• Phenotypic analysis of patients with PRIM1 mutations.

Main Results:

• Biallelic mutations in PRIM1 were identified in five individuals, establishing it as a novel disease gene.
• Patient cells exhibited significantly reduced PRIM1 protein levels.
• Replication fork asymmetry, increased interorigin distances, and replication stress were observed in patient cells.
• Prolonged S-phase duration and markedly impaired cell proliferation were evident, explaining extreme growth failure.
• Distinct phenotypic features, differing from those associated with DNA polymerase gene mutations, were noted.

Conclusions:

• PRIM1 mutations represent a newly identified cause of human genetic disease.
• PRIM1 deficiency leads to fundamental defects in DNA replication initiation and progression.
• The study highlights the critical and distinct developmental roles of the DNA primase subunit in human health.
• Further research is warranted to understand the specific phenotypic manifestations and developmental requirements associated with PRIM1 dysfunction.