@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 {147,
	title = {Activating Mutations Affecting the Dbl Homology Domain of SOS2 Cause Noonan Syndrome.},
	journal = {Hum Mutat},
	volume = {36},
	year = {2015},
	month = {2015 Nov},
	pages = {1080-7},
	abstract = {<p>The RASopathies constitute a family of autosomal-dominant disorders whose major features include facial dysmorphism, cardiac defects, reduced postnatal growth, variable cognitive deficits, ectodermal and skeletal anomalies, and susceptibility to certain malignancies. Noonan syndrome (NS), the commonest RASopathy, is genetically heterogeneous and caused by functional dysregulation of signal transducers and regulatory proteins with roles in the RAS/extracellular signal-regulated kinase (ERK) signal transduction pathway. Mutations in known disease genes account for approximately 80\% of affected individuals. Here, we report that missense mutations altering Son of Sevenless, Drosophila, homolog 2 (SOS2), which encodes a RAS guanine nucleotide exchange factor, occur in a small percentage of subjects with NS. Four missense mutations were identified in five unrelated sporadic cases and families transmitting NS. Disease-causing mutations affected three conserved residues located in the Dbl homology (DH) domain, of which two are directly involved in the intramolecular binding network maintaining SOS2 in its autoinhibited conformation. All mutations were found to promote enhanced signaling from RAS to ERK. Similar to NS-causing SOS1 mutations, the phenotype associated with SOS2 defects is characterized by normal development and growth, as well as marked ectodermal involvement. Unlike SOS1 mutations, however, those in SOS2 are restricted to the DH domain. </p>},
	keywords = {Adolescent, Adult, Alleles, Amino Acid Substitution, Child, DNA Mutational Analysis, Exome, Facies, Female, Genetic Association Studies, Genotype, Humans, Male, Models, Molecular, Mutation, Noonan Syndrome, Phenotype, Protein Conformation, Protein Interaction Domains and Motifs, Son of Sevenless Proteins, Young Adult},
	issn = {1098-1004},
	doi = {10.1002/humu.22834},
	author = {Cordeddu, Viviana and Yin, Jiani C and Gunnarsson, Cecilia and Virtanen, Carl and Drunat, S{\'e}verine and Lepri, Francesca and De Luca, Alessandro and Rossi, Cesare and Ciolfi, Andrea and Pugh, Trevor J and Bruselles, Alessandro and Priest, James R and Pennacchio, Len A and Lu, Zhibin and Danesh, Arnavaz and Quevedo, Rene and Hamid, Alaa and Martinelli, Simone and Pantaleoni, Francesca and Gnazzo, Maria and Daniele, Paola and Lissewski, Christina and Bocchinfuso, Gianfranco and Stella, Lorenzo and Odent, Sylvie and Philip, Nicole and Faivre, Laurence and Vlckova, Marketa and Seemanova, Eva and Digilio, Cristina and Zenker, Martin and Zampino, Giuseppe and Verloes, Alain and Dallapiccola, Bruno and Roberts, Amy E and Cav{\'e}, H{\'e}l{\`e}ne and Gelb, Bruce D and Neel, Benjamin G and Tartaglia, Marco}
}
