Capillary malformation/arteriovenous malformation (CM-AVM) syndrome is a rare disorder of the vascular (blood vessel) system.
The CM-AVM syndrome was first described in 2003. The syndrome is caused by a mutation in the RASA-1 gene, which functions in development of the vascular system. The mutation can be passed down from a parent or occur by chance (sporadically). It may take different forms in affected family members, with some having only small vascular birthmarks and some developing significant vessel malformations.