@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 {432, title = {Nemaline myopathy and distal arthrogryposis associated with an autosomal recessive~TNNT3~splice variant.}, journal = {Hum Mutat}, volume = {39}, year = {2018}, month = {2018 03}, pages = {383-388}, abstract = {

A male neonate presented with severe weakness, hypotonia, contractures and congenital scoliosis. Skeletal muscle specimens showed marked atrophy and degeneration of fast fibers with striking nemaline rods and hypertrophy of slow fibers that were ultrastructurally normal. A neuromuscular gene panel identified a homozygous essential splice variant in TNNT3 (chr11:1956150G~>~A, NM_006757.3:c.681+1G~>~A). TNNT3 encodes skeletal troponin-T and is associated with autosomal dominant distal arthrogryposis. TNNT3 has not previously been associated with nemaline myopathy (NM), a rare congenital myopathy linked to defects in proteins associated with thin filament structure and regulation. cDNA studies confirmed pathogenic consequences of the splice variant, eliciting exon-skipping and intron retention events leading to a frameshift. Western blot showed deficiency of troponin-T protein with secondary loss of troponin-I . We establish a homozygous splice variant in TNNT3 as the likely cause of severe congenital NM with distal arthrogryposis, characterized by specific involvement of Type-2 fibers and deficiency of troponin-T .

}, keywords = {Arthrogryposis, Genes, Recessive, Humans, Infant, Infant, Newborn, Male, Myopathies, Nemaline, RNA Splice Sites, RNA Splicing, RNA, Messenger, Troponin T}, issn = {1098-1004}, doi = {10.1002/humu.23385}, author = {Sandaradura, Sarah A and Bournazos, Adam and Mallawaarachchi, Amali and Cummings, Beryl B and Waddell, Leigh B and Jones, Kristi J and Troedson, Christopher and Sudarsanam, Annapurna and Nash, Benjamin M and Peters, Gregory B and Algar, Elizabeth M and MacArthur, Daniel G and North, Kathryn N and Brammah, Susan and Charlton, Amanda and Laing, Nigel G and Wilson, Meredith J and Davis, Mark R and Cooper, Sandra T} } @article {371, title = {Activation of a cryptic splice site in the mitochondrial elongation factor GFM1 causes combined OXPHOS deficiency.}, journal = {Mitochondrion}, volume = {34}, year = {2017}, month = {2017 05}, pages = {84-90}, abstract = {

We report the clinical, biochemical, and molecular findings in two brothers with encephalopathy and multi-systemic disease. Abnormal transferrin glycoforms were suggestive of a type I congenital disorder of glycosylation (CDG). While exome sequencing was negative for CDG related candidate genes, the testing revealed compound heterozygous mutations in the mitochondrial elongation factor G gene (GFM1). One of the mutations had been reported previously while the second, novel variant was found deep in intron 6, activating a cryptic splice site. Functional studies demonstrated decreased GFM1 protein levels, suggested disrupted assembly of mitochondrial complexes III and V and decreased activities of mitochondrial complexes I and IV, all indicating combined OXPHOS deficiency.

}, keywords = {Child, Child, Preschool, Congenital Abnormalities, Gene Expression, Humans, Infant, Infant, Newborn, Male, Mitochondrial Proteins, Oxidative Phosphorylation, Peptide Elongation Factor G, RNA Splice Sites}, issn = {1872-8278}, doi = {10.1016/j.mito.2017.02.004}, author = {Simon, Mariella T and Ng, Bobby G and Friederich, Marisa W and Wang, Raymond Y and Boyer, Monica and Kircher, Martin and Collard, Renata and Buckingham, Kati J and Chang, Richard and Shendure, Jay and Nickerson, Deborah A and Bamshad, Michael J and Van Hove, Johan L K and Freeze, Hudson H and Abdenur, Jose E} } @article {342, title = {MECR Mutations Cause Childhood-Onset Dystonia and Optic Atrophy, a Mitochondrial Fatty Acid Synthesis Disorder.}, journal = {Am J Hum Genet}, volume = {99}, year = {2016}, month = {2016 Dec 01}, pages = {1229-1244}, abstract = {

Mitochondrial fatty acid synthesis (mtFAS) is an evolutionarily conserved pathway essential for the function of the respiratory chain and several mitochondrial enzyme complexes. We report here a unique neurometabolic human disorder caused by defective mtFAS. Seven individuals from five unrelated families presented with childhood-onset dystonia, optic atrophy, and basal ganglia signal abnormalities on MRI. All affected individuals were found to harbor recessive mutations in MECR encoding the mitochondrial trans-2-enoyl-coenzyme A-reductase involved in human mtFAS. All six mutations are extremely rare in the general population, segregate with the disease in the families, and are predicted to be deleterious. The nonsense c.855T>G (p.Tyr285), c.247_250del (p.Asn83Hisfs4), and splice site c.830+2_830+3insT mutations lead to C-terminal truncation variants of MECR. The missense c.695G>A (p.Gly232Glu), c.854A>G (p.Tyr285Cys), and c.772C>T (p.Arg258Trp) mutations involve conserved amino acid residues, are located within the cofactor binding domain, and are predicted by structural analysis to have a destabilizing effect. Yeast modeling and complementation studies validated the pathogenicity of the MECR mutations. Fibroblast cell lines from affected individuals displayed reduced levels of both MECR and lipoylated proteins as well as defective respiration. These results suggest that mutations in MECR cause a distinct human disorder of the mtFAS pathway. The observation of decreased lipoylation raises the possibility of a potential therapeutic strategy.

}, keywords = {Basal Ganglia, Cells, Cultured, Child, Child, Preschool, Dystonic Disorders, Fatty Acids, Female, Fibroblasts, Genetic Complementation Test, Humans, Infant, Male, Mitochondria, Mitochondrial Diseases, Models, Molecular, Mutation, Mutation, Missense, Optic Atrophy, Oxidoreductases Acting on CH-CH Group Donors, Pedigree, RNA Splice Sites, Saccharomyces cerevisiae}, issn = {1537-6605}, doi = {10.1016/j.ajhg.2016.09.021}, author = {Heimer, Gali and Ker{\"a}t{\"a}r, Juha M and Riley, Lisa G and Balasubramaniam, Shanti and Eyal, Eran and Pietik{\"a}inen, Laura P and Hiltunen, J Kalervo and Marek-Yagel, Dina and Hamada, Jeffrey and Gregory, Allison and Rogers, Caleb and Hogarth, Penelope and Nance, Martha A and Shalva, Nechama and Veber, Alvit and Tzadok, Michal and Nissenkorn, Andreea and Tonduti, Davide and Renaldo, Florence and Kraoua, Ichraf and Panteghini, Celeste and Valletta, Lorella and Garavaglia, Barbara and Cowley, Mark J and Gayevskiy, Velimir and Roscioli, Tony and Silberstein, Jonathon M and Hoffmann, Chen and Raas-Rothschild, Annick and Tiranti, Valeria and Anikster, Yair and Christodoulou, John and Kastaniotis, Alexander J and Ben-Zeev, Bruria and Hayflick, Susan J} } @article {236, title = {Individual exome analysis in diagnosis and management of paediatric liver failure of indeterminate aetiology.}, journal = {J Hepatol}, volume = {61}, year = {2014}, month = {2014 Nov}, pages = {1056-63}, abstract = {

BACKGROUND \& AIMS: In children with liver failure, as many as half remain of indeterminate aetiology. This hinders timely consideration of optimal treatment options. We posit that a significant subset of these children harbour known inherited metabolic liver diseases with atypical presentation or novel inborn errors of metabolism. We investigated the utility of whole-exome sequencing in three children with advanced liver disease of indeterminate aetiology.

METHODS: Patient 1 was a 10 year-old female diagnosed with Wilson disease but no detectable ATP7B mutations, and decompensated liver cirrhosis who underwent liver transplant and subsequently developed onset of neurodegenerative disease. Patient 2 was a full-term 2 day-old male with fatal acute liver failure of indeterminate aetiology. Patient 3 was an 8 year-old female with progressive syndromic cholestasis of unknown aetiology since age 3 months.

RESULTS: Unbiased whole-exome sequencing of germline DNA revealed homozygous mutations in MPV17 and SERAC1 as the disease causing genes in patient 1 and 2, respectively. This is the first demonstration of SERAC1 loss-of-function associated fatal acute liver failure. Patient 1 expands the phenotypic spectrum of the MPV17-related hepatocerebral mitochondrial DNA depletion syndrome. Patient 3 was found to have syndromic cholestasis due to bi-allelic NOTCH2 mutations.

CONCLUSIONS: Our findings validate the application of whole-exome sequencing in the diagnosis and management of children with advanced liver disease of indeterminate aetiology, with the potential to enhance optimal selection of treatment options and adequate counselling of families. Moreover, whole-exome sequencing revealed a hitherto unrecognized phenotypic spectrum of inherited metabolic liver diseases.

}, keywords = {Amino Acid Sequence, Base Sequence, Carboxylic Ester Hydrolases, Child, Cholestasis, DNA Mutational Analysis, End Stage Liver Disease, Exome, Fatal Outcome, Female, Genes, Recessive, Hepatolenticular Degeneration, Heterozygote, Homozygote, Humans, Infant, Newborn, Liver Failure, Liver Failure, Acute, Male, Membrane Proteins, Mitochondrial Proteins, Molecular Sequence Data, Pedigree, Receptor, Notch2, RNA Splice Sites, Sequence Homology, Amino Acid}, issn = {1600-0641}, doi = {10.1016/j.jhep.2014.06.038}, author = {Vilarinho, S{\'\i}lvia and Choi, Murim and Jain, Dhanpat and Malhotra, Ajay and Kulkarni, Sanjay and Pashankar, Dinesh and Phatak, Uma and Patel, Mohini and Bale, Allen and Mane, Shrikant and Lifton, Richard P and Mistry, Pramod K} } @article {239, title = {Opsismodysplasia resulting from an insertion mutation in the SH2 domain, which destabilizes INPPL1.}, journal = {Am J Med Genet A}, volume = {164A}, year = {2014}, month = {2014 Sep}, pages = {2407-11}, keywords = {Adolescent, Amino Acid Sequence, Base Sequence, Child, Child, Preschool, Female, Humans, Infant, Molecular Sequence Data, Mutagenesis, Insertional, Mutation, Osteochondrodysplasias, Phosphatidylinositol-3,4,5-Trisphosphate 5-Phosphatases, Phosphoric Monoester Hydrolases, Protein Stability, Radiography, RNA Splice Sites, src Homology Domains}, issn = {1552-4833}, doi = {10.1002/ajmg.a.36640}, author = {Li, Bing and Krakow, Deborah and Nickerson, Deborah A and Bamshad, Michael J and Chang, Yong and Lachman, Ralph S and Yilmaz, Alev and Kayserili, H{\"u}lya and Cohn, Daniel H} }