Dr. Pevsner's laboratory found the somatic mutation (a change in DNA that occurs after conception and affects only part of the body) that causes SWS and port-wine birthmarks by performing whole genome sequencing on affected and unaffected tissue and blood samples from three individuals with SWS. They were able to identify one somatic mutation shared by all three affected samples a nucleotide transition in gene GNAQ on chromosome 9q21. In a separate analysis, the researchers confirmed the finding by detecting the mutation in 23 out of 26 tissue samples from subjects with SWS and 12 out of 13 samples from subjects with isolated port-wine birthmarks. The control samples, and most of the unaffected samples, did not possess the mutation. These analyses also revealed the surprising outcome that the gene involved in SWS is the same gene implicated in uveal melanoma, a type of melanoma that occurs in the eye.
Collaborating with Kennedy Krieger scientists was Douglas Marchuk, Ph.D., and his team at Duke University Medical Center, who further illuminated GNAQ's role in SWS. Within the body, GNAQ encodes a set of membrane proteins that ensure a set of signaling pathways within the cell are working correctly. However, in both SWS and port-wine stains, a mutation occurs in GNAQ that causes those sets of pathways to increase their activity, ultimately resulting in both conditions.
With the discovery of the gene and pathway involved in SWS and port-wine stains, researchers can now begin investigating drugs that selectively inhibit the implicated pathways. The link to melanoma may also influence research and lead to new directions for
|Contact: Megan Lustig|
Kennedy Krieger Institute