Genetic Heterogeneity in Cellular Angiofibromas

Area of Science:

• Oncology
• Genetics
• Pathology

Background:

• Cellular angiofibroma is a rare benign mesenchymal neoplasm.
• It shares similarities with spindle cell lipoma, often grouped in the 13q/RB1 family.
• Genetic analysis reveals underlying pathogenetic heterogeneity.

Purpose of the Study:

• To investigate the genetic basis of cellular angiofibroma.
• To identify distinct genetic pathways contributing to tumor development.
• To explore potential diagnostic implications of genetic findings.

Main Methods:

• Utilized G-banding/Karyotyping for chromosomal analysis.
• Employed array comparative genomic hybridization for copy number variations.
• Conducted RNA sequencing and direct sequencing for gene expression and mutations.

Main Results:

• One tumor exhibited del(13)(q12) with RB1 gene loss and reduced expression.
• Two tumors showed chromosome 8 abnormalities with PLAG1 gene fusions.
• Specific fusions identified: CTSB::PLAG1 and MIR99AHG::PLAG1, leading to elevated PLAG1 and IGF2 expression.

Conclusions:

• Identified two distinct genetic pathways in cellular angiofibromas.
• Pathway one involves the 13q/RB1 genetic alterations.
• Pathway two is characterized by PLAG1-chimeras, impacting gene expression.