ATRX driver mutation in a composite malignant pheochromocytoma.

Area of Science:

• Endocrinology
• Oncology
• Genetics

Background:

• Pheochromocytomas (PCCs) and paragangliomas (PGLs) are rare neuroendocrine tumors.
• Genetic mutations in susceptibility genes account for a significant proportion of PCCs/PGLs.
• Somatic ATRX mutations have been recently identified in SDH-associated hereditary PCCs/PGLs.

Observation:

• Whole-exome sequencing was performed on a patient with metastatic composite PCC lacking known genetic alterations.
• A somatic loss-of-function mutation in the ATRX gene was detected in tumor DNA.
• Transcriptional profiling revealed altered expression of neuronal development and miRNA/rRNA processing genes.

Findings:

• The tumor was classified into PCC/PGL cluster 2, distinct from SDH-mutated tumors.
• CpG island methylator phenotype was absent, and SNP array data showed a unique genomic profile.
• Alternative lengthening of telomeres was observed, suggesting ATRX dysfunction.

Implications:

• Somatic ATRX variants may act as a driver in sporadic PCC/PGL development.
• This study broadens the genetic landscape of PCCs/PGLs.
• Understanding ATRX's role could lead to new diagnostic or therapeutic strategies for PCCs/PGLs.