@article {958, title = {Autosomal recessive variants in alter the γ-tubulin ring complex leading to neurodevelopmental disease.}, journal = {iScience}, volume = {24}, year = {2021}, month = {2021 Jan 22}, pages = {101948}, abstract = {

Microtubules help building the cytoskeleton of neurons and other cells. Several components of the gamma-tubulin (γ-tubulin) complex have been previously reported in human neurodevelopmental diseases. We describe two siblings from a consanguineous Turkish family with dysmorphic features, developmental delay, brain malformation, and epilepsy carrying a homozygous mutation (p.Glu311Lys) in encoding the γ-tubulin complex 2 (GCP2) protein. This variant is predicted to disrupt the electrostatic interaction of GCP2 with GCP3. In primary fibroblasts carrying the variant, we observed a faint delocalization of γ-tubulin during the cell cycle but normal GCP2 protein levels. Through mass spectrometry, we observed dysregulation of multiple proteins involved in the assembly and organization of the cytoskeleton and the extracellular matrix, controlling cellular adhesion and of proteins crucial for neuronal homeostasis including axon guidance. In summary, our functional and proteomic studies link TUBGCP2 and the γ-tubulin complex to the development of the central nervous system in humans.

}, issn = {2589-0042}, doi = {10.1016/j.isci.2020.101948}, author = {G{\"u}ng{\"o}r, Serdal and Oktay, Yavuz and Hiz, Semra and Aranguren-Ib{\'a}{\~n}ez, {\'A}lvaro and Kalafatcilar, Ipek and Yaramis, Ahmet and Karaca, Ezgi and Yis, Uluc and Sonmezler, Ece and Ekinci, Burcu and Aslan, Mahmut and Yilmaz, Elmasnur and {\"O}zg{\"o}r, Bilge and Balaraju, Sunitha and Szabo, Nora and Laurie, Steven and Beltran, Sergi and MacArthur, Daniel G and Hathazi, Denisa and Topf, Ana and Roos, Andreas and Lochm{\"u}ller, Hanns and Vernos, Isabelle and Horvath, Rita} } @article {806, title = {Biallelic loss of function variants in SYT2 cause a treatable congenital onset presynaptic myasthenic syndrome.}, journal = {Am J Med Genet A}, volume = {182}, year = {2020}, month = {2020 10}, pages = {2272-2283}, abstract = {

Synaptotagmins are integral synaptic vesicle membrane proteins that function as calcium sensors and regulate neurotransmitter release at the presynaptic nerve terminal. Synaptotagmin-2 (SYT2), is the major isoform expressed at the neuromuscular junction. Recently, dominant missense variants in SYT2 have been reported as a rare cause of distal motor neuropathy and myasthenic syndrome, manifesting with stable or slowly progressive distal weakness of variable severity along with presynaptic NMJ impairment. These variants are thought to have a dominant-negative effect on synaptic vesicle exocytosis, although the precise pathomechanism remains to be elucidated. Here we report seven patients of five families, with biallelic loss of function variants in SYT2, clinically manifesting with a remarkably consistent phenotype of severe congenital onset hypotonia and weakness, with variable degrees of respiratory involvement. Electrodiagnostic findings were consistent with a presynaptic congenital myasthenic syndrome (CMS) in some. Treatment with an acetylcholinesterase inhibitor pursued in three patients showed clinical improvement with increased strength and function. This series further establishes SYT2 as a CMS-disease gene and expands its clinical and genetic spectrum to include recessive loss-of-function variants, manifesting as a severe congenital onset presynaptic CMS with potential treatment implications.

}, keywords = {Adolescent, Child, Child, Preschool, Female, Genetic Predisposition to Disease, Humans, Male, Muscle Hypotonia, Muscle Weakness, Mutation, Missense, Myasthenic Syndromes, Congenital, Pedigree, Phenotype, Synaptic Transmission, Synaptotagmin II}, issn = {1552-4833}, doi = {10.1002/ajmg.a.61765}, author = {Donkervoort, Sandra and Mohassel, Payam and Laugwitz, Lucia and Zaki, MAH S and Kamsteeg, Erik-Jan and Maroofian, Reza and Chao, Katherine R and Verschuuren-Bemelmans, Corien C and Horber, Veronka and Fock, Annemarie J M and McCarty, Riley M and Jain, Minal S and Biancavilla, Victoria and McMacken, Grace and Nalls, Matthew and Voermans, Nicol C and Elbendary, Hasnaa M and Snyder, Molly and Cai, Chunyu and Lehky, Tanya J and Stanley, Valentina and Iannaccone, Susan T and Foley, A Reghan and Lochm{\"u}ller, Hanns and Gleeson, Joseph and Houlden, Henry and Haack, Tobias B and Horvath, Rita and B{\"o}nnemann, Carsten G} } @article {756, title = {Congenital myasthenic syndrome with mild intellectual disability caused by a recurrent SLC25A1 variant.}, journal = {Eur J Hum Genet}, volume = {28}, year = {2020}, month = {2020 03}, pages = {373-377}, abstract = {

Congenital myasthenic syndromes (CMS) are a clinically and genetically heterogeneous group of disorders caused by mutations which lead to impaired neuromuscular transmission. SLC25A1 encodes a mitochondrial citrate carrier, associated mainly with the severe neurometabolic disease combined D-2- and L-2-hydroxyglutaric aciduria (D/L-2-HGA). We previously reported a single family with a homozygous missense variant in SLC25A1 with a phenotype restricted to relatively mild CMS with intellectual disability, but to date no additional cases of this CMS subtype had been reported. Here, we performed whole exome sequencing (WES) in three additional and unrelated families presenting with CMS and mild intellectual disability to identify the underlying causative gene. The WES analysis revealed the presence of a homozygous c.740G>A; p.(Arg247Gln) missense SLC25A1 variant, the same SLC25A1 variant as identified in the original family with this phenotype. Electron microscopy of muscle from two cases revealed enlarged and accumulated mitochondria. Haplotype analysis performed in two unrelated families suggested that this variant is a result of recurrent mutation and not a founder effect. This suggests that p.(Arg247Gln) is associated with a relatively mild CMS phenotype with subtle mitochondrial abnormalities, while other variants in this gene cause more severe neurometabolic disease. In conclusion, the p.(Arg247Gln) SLC25A1 variant should be considered in patients presenting with a presynaptic CMS phenotype, particularly with accompanying intellectual disability.

}, keywords = {Adult, Female, Haplotypes, Homozygote, Humans, Intellectual Disability, Male, Mitochondrial Proteins, Muscle, Skeletal, Mutation, Missense, Myasthenic Syndromes, Congenital, Organic Anion Transporters}, issn = {1476-5438}, doi = {10.1038/s41431-019-0506-2}, author = {Balaraju, Sunitha and Topf, Ana and McMacken, Grace and Kumar, Veeramani Preethish and Pechmann, Astrid and Roper, Helen and Vengalil, Seena and Polavarapu, Kiran and Nashi, Saraswati and MAHjan, Niranjan Prakash and Barbosa, Ines A and Deshpande, Charu and Taylor, Robert W and Cossins, Judith and Beeson, David and Laurie, Steven and Kirschner, Janbernd and Horvath, Rita and McFarland, Robert and Nalini, Atchayaram and Lochm{\"u}ller, Hanns} } @article {960, title = {Expanding the clinical and molecular spectrum of ATP6V1A related metabolic cutis laxa.}, journal = {J Inherit Metab Dis}, year = {2020}, month = {2020 Dec 15}, abstract = {

Several inborn errors of metabolism show cutis laxa as a highly recognizable feature. One group of these metabolic cutis laxa conditions is autosomal recessive cutis laxa type 2 caused by defects in v-ATPase components or the mitochondrial proline cycle. Besides cutis laxa, muscular hypotonia and cardiac abnormalities are hallmarks of autosomal recessive cutis laxa type 2D (ARCL2D) due to pathogenic variants in ATP6V1A encoding subunit A of the v-ATPase. Here, we report on three affected individuals from two families with ARCL2D in whom we performed whole exome and Sanger sequencing. We performed functional studies in fibroblasts from one individual, summarized all known probands{\textquoteright} clinical, molecular, and biochemical features and compared them, also to other metabolic forms of cutis laxa. We identified novel missense and the first nonsense variant strongly affecting ATP6V1A expression. All six ARCL2D affected individuals show equally severe cutis laxa and dysmorphism at birth. While for one no information was available, two died in infancy and three are now adolescents with mild or absent intellectual disability. Muscular weakness, ptosis, contractures, and elevated muscle enzymes indicated a persistent myopathy. In cellular studies, a fragmented Golgi compartment, a delayed Brefeldin A-induced retrograde transport and glycosylation abnormalities were present in fibroblasts from two individuals. This is the second and confirmatory report on pathogenic variants in ATP6V1A as the cause of this extremely rare condition and the first to describe a nonsense allele. Our data highlight the tremendous clinical variability of ATP6V1A related phenotypes even within the same family.

}, issn = {1573-2665}, doi = {10.1002/jimd.12341}, author = {Vogt, Guido and El Choubassi, Naji and Herczegfalvi, {\'A}gnes and K{\"o}lbel, Heike and Lekaj, Anja and Schara, Ulrike and Holtgrewe, Manuel and Krause, Sabine and Horvath, Rita and Schuelke, Markus and H{\"u}bner, Christoph and Mundlos, Stefan and Roos, Andreas and Lochm{\"u}ller, Hanns and Karcagi, Veronika and Kornak, Uwe and Fischer-Zirnsak, Bj{\"o}rn} } @article {765, title = {-related autosomal recessive encephalopathy in 2 Turkish children.}, journal = {Neurol Genet}, volume = {6}, year = {2020}, month = {2020 Feb}, pages = {e392}, abstract = {

Objective: This study presents the neurologic phenotypes of 2 brothers with a novel homozygous mutation that was identified in a large Turkish consanguineous cohort of neurogenetic diseases.

Methods: Whole-exome sequencing and bioinformatic analysis of consanguineous families with children affected by early-onset, neurogenetic disorders was performed using the RD-Connect Genome-Phenome Analysis Platform. We also performed clinical, EEG, and neuroimaging analyses in unaffected siblings and parents.

Results: We have identified a homozygous missense mutation in (p.Gly1278Ser, NM_001845.5:c.3832G>T) in 2 siblings affected by small vessel brain disease with periventricular leukoencephalopathy and ocular defects. Presenting symptoms included mild weakness, hemiparetic gait, pyramidal findings, and seizures, whereas their intellectual and behavioral functions were normal. Both parents and 5 of the siblings (3 boys and 2 girls) were heterozygous for the variant. They did not show any clinical or laboratory signs of small vessel disease.

Conclusions: has previously been associated with dominant small vessel disease of the brain and other organs, manifesting with high penetrance in heterozygous mutation carriers. Our findings provide evidence that -related encephalopathy can be inherited in an autosomal recessive manner, which is important for counseling, prognosis, and treatment. Genotype-phenotype correlations remain to be established.

}, issn = {2376-7839}, doi = {10.1212/NXG.0000000000000392}, author = {Yaramis, Ahmet and Lochm{\"u}ller, Hanns and Topf, Ana and Sonmezler, Ece and Yilmaz, Elmasnur and Hiz, Semra and Yis, Uluc and G{\"u}ng{\"o}r, Serdal and Ipek Polat, Ayse and Edem, Pinar and Beltran, Sergi and Laurie, Steven and Yaramis, Aysenur and Horvath, Rita and Oktay, Yavuz} } @article {755, title = {Severe neurodevelopmental disease caused by a homozygous TLK2 variant.}, journal = {Eur J Hum Genet}, volume = {28}, year = {2020}, month = {2020 03}, pages = {383-387}, abstract = {

A distinct neurodevelopmental phenotype characterised mainly by mild motor and language delay and facial dysmorphism, caused by heterozygous de novo or dominant variants in the TLK2 gene has recently been described. All cases reported carried either truncating variants located throughout the gene, or missense changes principally located at the C-terminal end of the protein mostly resulting in haploinsufficiency of TLK2. Through whole exome sequencing, we identified a homozygous missense variant in TLK2 in a patient showing more severe symptoms than those previously described, including cerebellar vermis hypoplasia and West syndrome. Both parents are heterozygous for the variant and clinically unaffected highlighting that recessive variants in TLK2 can also be disease causing and may act through a different pathomechanism.

}, keywords = {Adult, Cerebellum, Child, Developmental Disabilities, Female, Heterozygote, Homozygote, Humans, Infant, Male, Mutation, Missense, Nervous System Malformations, Pedigree, Protein Kinases, Spasms, Infantile}, issn = {1476-5438}, doi = {10.1038/s41431-019-0519-x}, author = {Topf, Ana and Oktay, Yavuz and Balaraju, Sunitha and Yilmaz, Elmasnur and Sonmezler, Ece and Yis, Uluc and Laurie, Steven and Thompson, Rachel and Roos, Andreas and MacArthur, Daniel G and Yaramis, Ahmet and G{\"u}ng{\"o}r, Serdal and Lochm{\"u}ller, Hanns and Hiz, Semra and Horvath, Rita} } @article {492, title = {Whole-exome sequencing identifies mutations in in a mild form of Carey-Fineman-Ziter syndrome.}, journal = {Neurol Genet}, volume = {4}, year = {2018}, month = {2018 Apr}, pages = {e226}, issn = {2376-7839}, doi = {10.1212/NXG.0000000000000226}, author = {Alrohaif, Hadil and Topf, Ana and Evangelista, Teresinha and Lek, Monkol and McArthur, Daniel and Lochm{\"u}ller, Hanns} } @article {443, title = {Complex phenotypes associated with STIM1 mutations in both coiled coil and EF-hand domains.}, journal = {Neuromuscul Disord}, volume = {27}, year = {2017}, month = {2017 Sep}, pages = {861-872}, abstract = {

Dominant mutations in STIM1 are a cause of three allelic conditions: tubular aggregate myopathy, Stormorken syndrome (a complex phenotype including myopathy, hyposplenism, hypocalcaemia and bleeding diathesis), and a platelet dysfunction disorder, York platelet syndrome. Previous reports have suggested a genotype-phenotype correlation with mutations in the N-terminal EF-hand domain associated with tubular aggregate myopathy, and a common mutation at p.R304W in a coiled coil domain associated with Stormorken syndrome. In this study individuals with STIM1 variants were identified by exome sequencing or STIM1 direct sequencing, and assessed for neuromuscular, haematological and biochemical evidence of the allelic disorders of STIM1. STIM1 mutations were investigated by fibroblast calcium imaging and 3D modelling. Six individuals with STIM1 mutations, including two novel mutations (c.262A>G (p.S88G) and c.911G>A (p.R304Q)), were identified. Extra-neuromuscular symptoms including thrombocytopenia, platelet dysfunction, hypocalcaemia or hyposplenism were present in 5/6 patients with mutations in both the EF-hand and CC domains. 3/6 patients had psychiatric disorders, not previously reported in STIM1 disease. Review of published STIM1 patients (n = 49) confirmed that neuromuscular symptoms are present in most patients. We conclude that the phenotype associated with activating STIM1 mutations frequently includes extra-neuromuscular features such as hypocalcaemia, hypo-/asplenia and platelet dysfunction regardless of mutation domain.

}, keywords = {Adult, Blood Platelet Disorders, Calcium, Cell Culture Techniques, DNA Mutational Analysis, Dyslexia, Erythrocytes, Abnormal, Family Health, Female, Fibroblasts, Genetic Association Studies, Humans, Ichthyosis, Magnetic Resonance Imaging, Male, Microscopy, Electron, Middle Aged, Migraine Disorders, Miosis, Models, Molecular, Muscle Fatigue, Muscle, Skeletal, Mutation, Myopathies, Structural, Congenital, NAD, Neoplasm Proteins, Spleen, Stromal Interaction Molecule 1}, issn = {1873-2364}, doi = {10.1016/j.nmd.2017.05.002}, author = {Harris, Elizabeth and Burki, Umar and Marini-Bettolo, Chiara and Neri, Marcella and Scotton, Chiara and Hudson, Judith and Bertoli, Marta and Evangelista, Teresinha and Vroling, Bas and Polvikoski, Tuomo and Roberts, Mark and Topf, Ana and Bushby, Kate and McArthur, Daniel and Lochm{\"u}ller, Hanns and Ferlini, Alessandra and Straub, Volker and Barresi, Rita} } @article {363, title = {International Cooperation to Enable the Diagnosis of All Rare Genetic Diseases.}, journal = {Am J Hum Genet}, volume = {100}, year = {2017}, month = {2017 May 04}, pages = {695-705}, abstract = {

Provision of a molecularly confirmed diagnosis in a timely manner for children and adults with rare genetic diseases shortens their "diagnostic odyssey," improves disease management, and fosters genetic counseling with respect to recurrence risks while assuring reproductive choices. In a general clinical genetics setting, the current diagnostic rate is approximately 50\%, but for those who do not receive a molecular diagnosis after the initial genetics evaluation, that rate is much lower. Diagnostic success for these more challenging affected individuals depends to a large extent on progress in the discovery of genes associated with, and mechanisms underlying, rare diseases. Thus, continued research is required for moving toward a more complete catalog of disease-related genes and variants. The International Rare Diseases Research Consortium (IRDiRC) was established in 2011 to bring together researchers and organizations invested in rare disease research to develop a means of achieving molecular diagnosis for all rare diseases. Here, we review the current and future bottlenecks to gene discovery and suggest strategies for enabling progress in this regard. Each successful discovery will define potential diagnostic, preventive, and therapeutic opportunities for the corresponding rare disease, enabling precision medicine for this patient population.

}, keywords = {Databases, Factual, Exome, Genome, Human, Humans, International Cooperation, Rare Diseases}, issn = {1537-6605}, doi = {10.1016/j.ajhg.2017.04.003}, author = {Boycott, Kym M and Rath, Ana and Chong, Jessica X and Hartley, Taila and Alkuraya, Fowzan S and Baynam, Gareth and Brookes, Anthony J and Brudno, Michael and Carracedo, Angel and den Dunnen, Johan T and Dyke, Stephanie O M and Estivill, Xavier and Goldblatt, Jack and Gonthier, Catherine and Groft, Stephen C and Gut, Ivo and Hamosh, Ada and Hieter, Philip and H{\"o}hn, Sophie and Hurles, Matthew E and Kaufmann, Petra and Knoppers, Bartha M and Krischer, Jeffrey P and Macek, Milan and Matthijs, Gert and Olry, Annie and Parker, Samantha and Paschall, Justin and Philippakis, Anthony A and Rehm, Heidi L and Robinson, Peter N and Sham, Pak-Chung and Stefanov, Rumen and Taruscio, Domenica and Unni, Divya and Vanstone, Megan R and Zhang, Feng and Brunner, Han and Bamshad, Michael J and Lochm{\"u}ller, Hanns} }