Genetics of Central Nervous System Arteriovenous Malformations (AVM): Genotype-Phenotype Correlation and Prognostic Impact on Patients With AVM

Cerebral and medullary arteriovenous malformations (AVMs) are morphologically abnormal vessels located on the surface or in the cerebral or medullary parenchyma. These vascular lesions cause the arterial and venous networks to communicate pathologically, creating an arteriovenous shunt.

The prevalence of cerebral Cerebral and medullary AVMs in general population is difficult to establish given the rarity of the condition. However, it is estimated at around 1 per 10,000 inhabitants (0.01%). About 15-20% of the cerebral vascular accidents are asymptomatic at the time of diagnosis. The occurrence of intracranial haemorrhage is the most important prognostic factor because it is associated with a significant morbidity and mortality. The management of an AVM is usually carried out in a multidisciplinary way, combining interventional neuroradiology, neurosurgery and vascular neurology.

The genetic, molecular and cellular mechanisms that cause vascular malformations of the central nervous system are partially known. Several recent research works highlight mutations in the RAS-MAPK or MAPK-ERK signalling pathway in AVMs. In cases of cerebral AVMs considered to be sporadic, a somatic KRAS/BRAF mutation has recently been demonstrated in tissue samples of operated AVMs.

Except in the case of Hereditary Haemorrhagic Telangiectasia (HHT or Rendu-Osler-Weber syndrome), the influence of genetic damage on the prognosis of AVM is poorly known. It is also interesting to note that genetic screening is not routinely performed in patients with cerebro-medullary AVMs and that therefore the prevalence of these clinical entities in patients with AVMs is not known.