Although the finding is based on samples from only 53 people, the researchers hope that their findings will be confirmed and maybe eventually lead to new therapies.
'This is a complete game changer for those with Sturge-Weber syndrome and the millions born with port-wine birthmarks', said study author Dr Anne Comi, director of the Kennedy Krieger Institute's Hunter Nelson Sturge-Weber Center. 'Now that we know the underlying genetic mutation responsible for both conditions, we're hopeful that we can move quickly towards targeted therapies, offering families the promise of new treatments for the first time'.
Port-wine stains are birthmarks that affect three in every 1,000 newborns and are caused by abnormal development of blood vessels in the skin. They can occur anywhere on the body, but if present on the forehead or scalp, may indicate Sturge-Weber syndrome. This is a neurological condition that can cause glaucoma, epilepsy and learning difficulties, affecting between one in 20,000 to 50,000 newborns.
Sturge-Weber syndrome and port-wine stains appear to be caused by the same mutation that occurs before birth. The mutation is a somatic or acquired mutation, which cannot be passed on from parents to children. When the mutation occurs early in development, children are thought to develop Sturge-Weber syndrome. If it happens later in development, port-wine stains are the result.
The research team used several samples from three people affected by Sturge-Weber syndrome. As the mutation affects only certain cells, resulting in the affected cells having a different genotype from other cells (also known as mosaicism), the researchers could compare visibly affected and normal tissue. After finding a mutation in the GNAQ gene, they confirmed their discovery using samples from another 50 people with Sturge-Weber syndrome, port-wine stains or neither condition.
A single gene mutation was long thought to be the cause of both disorders. 'We suspected that a somatic mutation was the cause for decades now, but the technology to test the theory didn’t exist', said co-researcher Jonathan Pevsner.
Karen Ball, president of the Sturge-Weber Foundation, said: 'This is a momentous advancement that is thrilling as both an advocate and parent of an affected child'.