Genetic insights reveal new targets for treating extracranial arteriovenous malformations

Our genes underlie all aspects of life, from our looks to how our cells behave. This includes diseases, as genetic changes can underlie the development and progression of certain health problems. This is true for arteriovenous malformations (AVMs), vascular anomalies that are known to be life-threatening. However, the biological mechanisms driving their growth have remained unclear, until now.

AVMs are tangled clusters of abnormal blood vessels that can cause pain, bleeding, and even heart failure. While they can occur anywhere in the body, those found outside the brain, termed "extracranial AVMs", are particularly complex and invasive. These AVMs often require surgery and have high rates of recurrence.

Now, recent findings from The University of Osaka, published in Virchows Archiv: European Journal of Pathology, have found and analyzed genes to help pave the way for new and targeted AVM therapies.

We analyzed tissue samples from 30 patients, representing the world's largest number of extracranial AVM cases subjected to genetic analysis together. We hoped to find information that could help us define the mechanism behind the disease in relation to genetic mutations."

Katsutoshi Hirose, first author

They found that nearly half of the patients carried mutations in the RAS/RAF/MAPK signaling pathway, which controls how cells grow and communicate. These mutations were linked to the characteristic abnormal vascular morphology and were frequently detected in younger female patients.

Through analysis of the causative genes, RNA, proteins, clinical findings, and the tissue pathology, the team discovered that the small, tangled vessels (called the nidus) within the AVMs exhibited increased activity in certain genes. One gene in particular, MAP4K4, was highly expressed in the nidus and may play a key role in AVM development. MAP4K4 ordinarily regulates cell movement and blood vessel growth. The researchers suggest the gene may thus also be responsible for the pathological angiogenesis of AVMs.

Intriguingly, ERK, a downstream effector of the RAS/RAF/MAPK signaling pathway, exhibited increased activity in all AVM cases - including in those without detectable mutations. "Clinical trials involving inhibitors of this signaling pathway are already underway internationally and may provide a promising new direction for AVM treatment," explains Yumiko Hori, senior author.

With few effective treatments, no known cure and a high likelihood of recurrence, these findings offer new hope. The study highlights the potential for effective precision therapies to treat AVMs without invasive surgery.