@article {728,
	title = {Pathogenic Variants in GPC4 Cause Keipert Syndrome.},
	journal = {Am J Hum Genet},
	volume = {104},
	year = {2019},
	month = {2019 May 02},
	pages = {914-924},
	abstract = {<p>Glypicans are a family of cell-surface heparan sulfate proteoglycans that regulate growth-factor signaling during development and are thought to play a role in the regulation of morphogenesis. Whole-exome sequencing of the Australian family that defined Keipert syndrome (nasodigitoacoustic syndrome) identified a hemizygous truncating variant in the gene encoding glypican 4 (GPC4). This variant, located in the final exon of GPC4, results in premature termination of the protein 51 amino acid residues prior to the stop codon, and in concomitant loss of functionally important N-linked glycosylation (Asn514) and glycosylphosphatidylinositol (GPI) anchor (Ser529) sites. We subsequently identified seven affected males from five additional kindreds with novel and predicted pathogenic variants in GPC4. Segregation analysis and X-inactivation studies in carrier females provided supportive evidence that the GPC4 variants caused the condition. Furthermore, functional studies of recombinant protein suggested that the truncated proteins p.Gln506 and p.Glu496 were less stable than the wild type. Clinical features of Keipert syndrome included a prominent forehead, a flat midface, hypertelorism, a broad nose, downturned corners of mouth, and digital abnormalities, whereas cognitive impairment and deafness were variable features. Studies of Gpc4 knockout mice showed evidence of the two primary features of Keipert syndrome: craniofacial abnormalities and digital abnormalities. Phylogenetic analysis demonstrated that GPC4 is most closely related to GPC6, which is associated with a bone dysplasia that has a phenotypic overlap with Keipert syndrome. Overall, we have shown that pathogenic variants in GPC4 cause a loss of function that results in Keipert syndrome, making GPC4 the third human glypican to be linked to a genetic syndrome.</p>},
	issn = {1537-6605},
	doi = {10.1016/j.ajhg.2019.02.026},
	author = {Amor, David J and Stephenson, Sarah E M and Mustapha, Mirna and Mensah, Martin A and Ockeloen, Charlotte W and Lee, Wei Shern and Tankard, Rick M and Phelan, Dean G and Shinawi, Marwan and de Brouwer, Arjan P M and Pfundt, Rolph and Dowling, Cari and Toler, Tomi L and Sutton, V Reid and Agolini, Emanuele and Rinelli, Martina and Capolino, Rossella and Martinelli, Diego and Zampino, Giuseppe and Dumi{\'c}, Miroslav and Reardon, William and Shaw-Smith, Charles and Leventer, Richard J and Delatycki, Martin B and Kleefstra, Tjitske and Mundlos, Stefan and Mortier, Geert and Bahlo, Melanie and Allen, Nicola J and Lockhart, Paul J}
}
@article {319,
	title = {Mutations in the TGF-β repressor SKI cause Shprintzen-Goldberg syndrome with aortic aneurysm.},
	journal = {Nat Genet},
	volume = {44},
	year = {2012},
	month = {2012 Nov},
	pages = {1249-54},
	abstract = {<p>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). However, the location and character of many of the causal mutations in LDS intuitively imply diminished TGF-β signaling. 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 aneurysm. We identified causative variation in ten individuals with SGS in the proto-oncogene SKI, a known repressor of TGF-β activity. 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.</p>},
	keywords = {Animals, Aortic Aneurysm, Arachnodactyly, Cells, Cultured, Craniosynostoses, DNA-Binding Proteins, Fibroblasts, Humans, Loeys-Dietz Syndrome, Marfan Syndrome, Mice, Mutation, Phenotype, Phosphorylation, Proto-Oncogene Proteins, Signal Transduction, Transforming Growth Factor beta, Zebrafish},
	issn = {1546-1718},
	doi = {10.1038/ng.2421},
	author = {Doyle, Alexander J and Doyle, Jefferson J and Bessling, Seneca L and Maragh, Samantha and Lindsay, Mark E and Schepers, Dorien and Gillis, Elisabeth and Mortier, Geert and Homfray, Tessa and Sauls, Kimberly and Norris, Russell A and Huso, Nicholas D and Leahy, Dan and Mohr, David W and Caulfield, Mark J and Scott, Alan F and Destr{\'e}e, Anne and Hennekam, Raoul C and Arn, Pamela H and Curry, Cynthia J and Van Laer, Lut and McCallion, Andrew S and Loeys, Bart L and Dietz, Harry C}
}
