@article {945, title = {Biallelic in-frame deletion in TRAPPC4 in a family with developmental delay and cerebellar atrophy.}, journal = {Brain}, volume = {143}, year = {2020}, month = {2020 10 01}, pages = {e83}, keywords = {Atrophy, Cerebellar Diseases, Humans, Intellectual Disability, Sequence Deletion}, issn = {1460-2156}, doi = {10.1093/brain/awaa256}, author = {Saad, Ahmed K and Marafi, Dana and Mitani, Tadahiro and Jolly, Angad and Du, Haowei and Elbendary, Hasnaa M and Jhangiani, Shalini N and Akdemir, Zeynep C and Gibbs, Richard A and Hunter, Jill V and Carvalho, Claudia M B C and Pehlivan, Davut and Posey, Jennifer E and Zaki, MAH S and Lupski, James R} } @article {738, title = {Deficiencies in vesicular transport mediated by TRAPPC4 are associated with severe syndromic intellectual disability.}, journal = {Brain}, volume = {143}, year = {2020}, month = {2020 01 01}, pages = {112-130}, abstract = {

The conserved transport protein particle (TRAPP) complexes regulate key trafficking events and are required for autophagy. TRAPPC4, like its yeast Trs23 orthologue, is a core component of the TRAPP complexes and one of the essential subunits for guanine nucleotide exchange factor activity for Rab1 GTPase. Pathogenic variants in specific TRAPP subunits are associated with neurological disorders. We undertook exome sequencing in three unrelated families of Caucasian, Turkish and French-Canadian ethnicities with seven affected children that showed features of early-onset seizures, developmental delay, microcephaly, sensorineural deafness, spastic quadriparesis and progressive cortical and cerebellar atrophy in an effort to determine the genetic aetiology underlying neurodevelopmental disorders. All seven affected subjects shared the same identical rare, homozygous, potentially pathogenic variant in a non-canonical, well-conserved splice site within TRAPPC4 (hg19:chr11:g.118890966A>G; TRAPPC4: NM_016146.5; c.454+3A>G). Single nucleotide polymorphism array analysis revealed there was no haplotype shared between the tested Turkish and Caucasian families suggestive of a variant hotspot region rather than a founder effect. In silico analysis predicted the variant to cause aberrant splicing. Consistent with this, experimental evidence showed both a reduction in full-length transcript levels and an increase in levels of a shorter transcript missing exon 3, suggestive of an incompletely penetrant splice defect. TRAPPC4 protein levels were significantly reduced whilst levels of other TRAPP complex subunits remained unaffected. Native polyacrylamide gel electrophoresis and size exclusion chromatography demonstrated a defect in TRAPP complex assembly and/or stability. Intracellular trafficking through the Golgi using the marker protein VSVG-GFP-ts045 demonstrated significantly delayed entry into and exit from the Golgi in fibroblasts derived from one of the affected subjects. Lentiviral expression of wild-type TRAPPC4 in these fibroblasts restored trafficking, suggesting that the trafficking defect was due to reduced TRAPPC4 levels. Consistent with the recent association of the TRAPP complex with autophagy, we found that the fibroblasts had a basal autophagy defect and a delay in autophagic flux, possibly due to unsealed autophagosomes. These results were validated using a yeast trs23 temperature sensitive variant that exhibits constitutive and stress-induced autophagic defects at permissive temperature and a secretory defect at restrictive temperature. In summary we provide strong evidence for pathogenicity of this variant in a member of the core TRAPP subunit, TRAPPC4 that associates with vesicular trafficking and autophagy defects. This is the first report of a TRAPPC4 variant, and our findings add to the growing number of TRAPP-associated neurological disorders.

}, keywords = {Atrophy, Autophagy, Cerebellum, Cerebral Cortex, Child, Child, Preschool, Craniofacial Abnormalities, Deafness, Developmental Disabilities, Epilepsy, Female, Fibroblasts, Hearing Loss, Sensorineural, Humans, Infant, Infant, Newborn, Intellectual Disability, Male, Microcephaly, Microscopy, Fluorescence, Muscle Spasticity, Nerve Tissue Proteins, Neurodevelopmental Disorders, Pedigree, Quadriplegia, RNA Splice Sites, Syndrome, Vesicular Transport Proteins}, issn = {1460-2156}, doi = {10.1093/brain/awz374}, author = {Van Bergen, Nicole J and Guo, Yiran and Al-Deri, Noraldin and Lipatova, Zhanna and Stanga, Daniela and Zhao, Sarah and Murtazina, Rakhilya and Gyurkovska, Valeriya and Pehlivan, Davut and Mitani, Tadahiro and Gezdirici, Alper and Antony, Jayne and Collins, Felicity and Willis, Mary J H and Coban Akdemir, Zeynep H and Liu, Pengfei and Punetha, Jaya and Hunter, Jill V and Jhangiani, Shalini N and Fatih, Jawid M and Rosenfeld, Jill A and Posey, Jennifer E and Gibbs, Richard A and Karaca, Ender and Massey, Sean and Ranasinghe, Thisara G and Sleiman, Patrick and Troedson, Chris and Lupski, James R and Sacher, Michael and Segev, Nava and Hakonarson, Hakon and Christodoulou, John} } @article {243, title = {Monoallelic and biallelic mutations in MAB21L2 cause a spectrum of major eye malformations.}, journal = {Am J Hum Genet}, volume = {94}, year = {2014}, month = {2014 Jun 05}, pages = {915-23}, abstract = {

We identified four different missense mutations in the single-exon gene MAB21L2 in eight individuals with bilateral eye malformations from five unrelated families via three independent exome sequencing projects. Three mutational events altered the same amino acid (Arg51), and two were identical de novo mutations (c.151C>T [p.Arg51Cys]) in unrelated children with bilateral anophthalmia, intellectual disability, and rhizomelic skeletal dysplasia. c.152G>A (p.Arg51His) segregated with autosomal-dominant bilateral colobomatous microphthalmia in a large multiplex family. The fourth heterozygous mutation (c.145G>A [p.Glu49Lys]) affected an amino acid within two residues of Arg51 in an adult male with bilateral colobomata. In a fifth family, a homozygous mutation (c.740G>A [p.Arg247Gln]) altering a different region of the protein was identified in two male siblings with bilateral retinal colobomata. In mouse embryos, Mab21l2 showed strong expression in the developing eye, pharyngeal arches, and limb bud. As predicted by structural homology, wild-type MAB21L2 bound single-stranded RNA, whereas this activity was lost in all altered forms of the protein. MAB21L2 had no detectable nucleotidyltransferase activity in~vitro, and its function remains unknown. Induced expression of wild-type MAB21L2 in human embryonic kidney 293 cells increased phospho-ERK (pERK1/2) signaling. Compared to the wild-type and p.Arg247Gln proteins, the proteins with the Glu49 and Arg51 variants had increased stability. Abnormal persistence of pERK1/2 signaling in MAB21L2-expressing cells during development is a plausible pathogenic mechanism for the heterozygous mutations. The phenotype associated with the homozygous mutation might be a consequence of complete loss of MAB21L2 RNA binding, although the cellular function of this interaction remains unknown.

}, keywords = {Adult, Alleles, Animals, Anophthalmos, Brain Diseases, Metabolic, Inborn, Coloboma, Corneal Opacity, Exome, Eye Proteins, Female, Gene Expression, HEK293 Cells, Heterozygote, Homozygote, Humans, Intellectual Disability, Intracellular Signaling Peptides and Proteins, Male, Mice, Microcephaly, Microphthalmos, Mutation, Missense, Pedigree, Phenotype, Protein Conformation, Signal Transduction}, issn = {1537-6605}, doi = {10.1016/j.ajhg.2014.05.005}, author = {Rainger, Joe and Pehlivan, Davut and Johansson, Stefan and Bengani, Hemant and Sanchez-Pulido, Luis and Williamson, Kathleen A and Ture, Mehmet and Barker, Heather and Rosendahl, Karen and Spranger, J{\"u}rgen and Horn, Denise and Meynert, Alison and Floyd, James A B and Prescott, Trine and Anderson, Carl A and Rainger, Jacqueline K and Karaca, Ender and Gonzaga-Jauregui, Claudia and Jhangiani, Shalini and Muzny, Donna M and Seawright, Anne and Soares, Dinesh C and Kharbanda, Mira and Murday, Victoria and Finch, Andrew and Gibbs, Richard A and van Heyningen, Veronica and Taylor, Martin S and Yakut, Tahsin and Knappskog, Per M and Hurles, Matthew E and Ponting, Chris P and Lupski, James R and Houge, Gunnar and FitzPatrick, David R} } @article {272, title = {Whole-exome sequencing links TMCO1 defect syndrome with cerebro-facio-thoracic dysplasia.}, journal = {Eur J Hum Genet}, volume = {22}, year = {2014}, month = {2014 Sep}, pages = {1145-8}, abstract = {

Whole-exome sequencing (WES) is a type of disruptive technology that has tremendous influence on human and clinical genetics research. An efficient and cost-effective method, WES is now widely used as a diagnostic tool for identifying the molecular basis of genetic syndromes that are often challenging to diagnose. Here we report a patient with a clinical diagnosis of cerebro-facio-thoracic dysplasia (CFTD; MIM$\#$213980) in whom we identified a homozygous splice-site mutation in the transmembrane and coiled-coil domains 1 (TMCO1) gene using WES. TMCO1 mutations cause craniofacial dysmorphism, skeletal anomalies characterized by multiple malformations of the vertebrae and ribs, and intellectual disability (MIM$\#$614132). A retrospective review revealed that clinical manifestations of both syndromes are very similar and overlap remarkably. We propose that mutations of TMCO1 are not only responsible for craniofacial dysmorphism, skeletal anomalies and mental retardation syndrome but also for CFTD.

}, keywords = {Abnormalities, Multiple, Exome, Humans, Infant, Intellectual Disability, Male, Membrane Proteins, Mutation, Protein Isoforms}, issn = {1476-5438}, doi = {10.1038/ejhg.2013.291}, author = {Pehlivan, Davut and Karaca, Ender and Aydin, Hatip and Beck, Christine R and Gambin, Tomasz and Muzny, Donna M and Bilge Geckinli, B and Karaman, Ali and Jhangiani, Shalini N and Gibbs, Richard A and Lupski, James R} }