Mutations in the TGF-β repressor SKI cause Shprintzen-Goldberg syndrome with aortic aneurysm

Abstract

Harry Dietz and colleagues report the identification of mutations in SKI in Shprintzen-Goldberg syndrome, which shares features with Marfan syndrome and Loeys-Dietz syndrome. SKI encodes a known repressor of TGF-β activity, and this work provides evidence for paradoxical increased TGF-β signaling as the mechanism underlying these related syndromes. Elevated transforming growth factor (TGF)-β signaling has been implicated in the pathogenesis of syndromic presentations of aortic aneurysm, including Marfan syndrome (MFS) and Loeys-Dietz syndrome (LDS)1,2,3,4. However, the location and character of many of the causal mutations in LDS intuitively imply diminished TGF-β signaling5. Taken together, these data have engendered controversy regarding the specific role of TGF-β in disease pathogenesis. Shprintzen-Goldberg syndrome (SGS) has considerable phenotypic overlap with MFS and LDS, including aortic aneurysm6,7,8. We identified causative variation in ten individuals with SGS in the proto-oncogene SKI, a known repressor of TGF-β activity9,10. Cultured dermal fibroblasts from affected individuals showed enhanced activation of TGF-β signaling cascades and higher expression of TGF-β–responsive genes relative to control cells. Morpholino-induced silencing of SKI paralogs in zebrafish recapitulated abnormalities seen in humans with SGS. These data support the conclusions that increased TGF-β signaling is the mechanism underlying SGS and that high signaling contributes to multiple syndromic presentations of aortic aneurysm.