The causes of arteriovenous malformation (AVM) are not known. Because it appears to occur at birth or to form soon after, doctors suspect a genetic link. Doctors believe it is most often a congenital condition and may have links to genetic mutations in chromosome 7; however, the exact process is still being researched. Injury to the central nervous system may cause AVMs to form later in life. Also under investigation are the causes behind lesions related to AVM, such as familial cavernous malformations (when capillaries grow together), ataxia telangiectasia (a rare childhood disease of the central nervous system) and other hereditary conditions.