Multiple Brain Developmental Venous Anomalies as a Marker for Constitutional Mismatch Repair Deficiency Syndrome.

The occurrence of multiple developmental venous anomalies in all our patients with CMMRD suggests that developmental venous anomalies may be a characteristic of this syndrome that has not been previously described. If confirmed, this quantifiable feature can be added to the current scoring system and could result in early implementation of genetic testing and surveillance protocols, which can be life-saving for these patients.