5q14.3 neurocutaneous syndrome: a novel continguous gene syndrome caused by simultaneous deletion of RASA1 and MEF2C.

Haploinsufficiency of RASA1, located on chromosome 5q14.3, has been identified as the etiology underlying the disorder capillary malformation-arteriovenous malformation (CM-AVM). Recently, haploinsufficiency of MEF2C, located 1.33 Mb distal to RASA1 on chromosome 5q14.3, has been implicated as the genetic etiology underlying a complex array of deficits including mental retardation, hypotonia, absent speech, seizures, and brain anomalies. Here we report a patient who is haploinsufficient in both RASA1 and MEF2C who presents with dermatologic and neurologic abnormalities that constitute a 5q14.3 neurocutaneous syndrome. This finding highlights the need to assess for CM-AVM in patients with neurologic features consistent with MEF2C haploinsufficiency, and vice versa.