@article {957, title = {Multiomic analysis elucidates Complex I deficiency caused by a deep intronic variant in NDUFB10.}, journal = {Hum Mutat}, volume = {42}, year = {2021}, month = {2021 Jan}, pages = {19-24}, abstract = {

The diagnosis of Mendelian disorders following uninformative exome and genome sequencing remains a challenging and often unmet need. Following uninformative exome and genome sequencing of a family quartet including two siblings with suspected mitochondrial disorder, RNA sequencing (RNAseq) was pursued in one sibling. Long-read amplicon sequencing was used to determine and quantify transcript structure. Immunoblotting studies and quantitative proteomics were performed to demonstrate functional impact. Differential expression analysis of RNAseq data identified significantly decreased expression of the mitochondrial OXPHOS Complex I subunit NDUFB10 associated with a cryptic exon in intron 1 of NDUFB10, that included an in-frame stop codon. The cryptic exon contained a rare intronic variant that was homozygous in both affected siblings. Immunoblot and quantitative proteomic analysis of fibroblasts revealed decreased abundance of Complex I subunits, providing evidence of isolated Complex I deficiency. Through multiomic analysis we present data implicating a deep intronic variant in NDUFB10 as the cause of mitochondrial disease in two individuals, providing further support of the gene-disease association. This study highlights the importance of transcriptomic and proteomic analyses as complementary diagnostic tools in patients undergoing genome-wide diagnostic evaluation.

}, issn = {1098-1004}, doi = {10.1002/humu.24135}, author = {Helman, Guy and Compton, Alison G and Hock, Daniella H and Walkiewicz, Marzena and Brett, Gemma R and Pais, Lynn and Tan, Tiong Y and De Paoli-Iseppi, Ricardo and Clark, Michael B and Christodoulou, John and White, Susan M and Thorburn, David R and Stroud, David A and Stark, Zornitza and Simons, Cas} } @article {791, title = {Distinct effects on mRNA export factor GANP underlie neurological disease phenotypes and alter gene expression depending on intron content.}, journal = {Hum Mol Genet}, volume = {29}, year = {2020}, month = {2020 06 03}, pages = {1426-1439}, abstract = {

Defects in the mRNA export scaffold protein GANP, encoded by the MCM3AP gene, cause autosomal recessive early-onset peripheral neuropathy with or without intellectual disability. We extend here the phenotypic range associated with MCM3AP variants, by describing a severely hypotonic child and a sibling pair with a progressive encephalopathic syndrome. In addition, our analysis of skin fibroblasts from affected individuals from seven unrelated families indicates that disease variants result in depletion of GANP except when they alter critical residues in the Sac3 mRNA binding domain. GANP depletion was associated with more severe phenotypes compared with the Sac3 variants. Patient fibroblasts showed transcriptome alterations that suggested intron content-dependent regulation of gene expression. For example, all differentially expressed intronless genes were downregulated, including ATXN7L3B, which couples mRNA export to transcription activation by association with the TREX-2 and SAGA complexes. Our results provide insight into the molecular basis behind genotype-phenotype correlations in MCM3AP-associated disease and suggest mechanisms by which GANP defects might alter RNA metabolism.

}, issn = {1460-2083}, doi = {10.1093/hmg/ddaa051}, author = {Woldegebriel, Rosa and Kvist, Jouni and Andersson, Noora and {\~O}unap, Katrin and Reinson, Karit and Wojcik, Monica H and Bijlsma, Emilia K and Hoffer, Mariette J V and Ryan, Monique M and Stark, Zornitza and Walsh, Maie and Cuppen, Inge and van den Boogaard, Marie-Jose H and Bharucha-Goebel, Diana and Donkervoort, Sandra and Winchester, Sara and Zori, Roberto and B{\"o}nnemann, Carsten G and Maroofian, Reza and O{\textquoteright}Connor, Emer and Houlden, Henry and Zhao, Fang and Carp{\'e}n, Olli and White, Matthew and Sreedharan, Jemeen and Stewart, Murray and Ylikallio, Emil and Tyynismaa, Henna} } @article {968, title = {Evaluating systematic reanalysis of clinical genomic data in rare disease from single center experience and literature review.}, journal = {Mol Genet Genomic Med}, volume = {8}, year = {2020}, month = {2020 11}, pages = {e1508}, abstract = {

BACKGROUND: Our primary aim was to evaluate the systematic reanalysis of singleton exome sequencing (ES) data for unsolved cases referred for any indication. A secondary objective was to undertake a literature review of studies examining the reanalysis of genomic data from unsolved cases.

METHODS: We examined data from 58 unsolved cases referred between June 2016 and March 2017. First reanalysis at 4-13~months after the initial report considered genes newly associated with disease since the original analysis; second reanalysis at 9-18~months considered all disease-associated genes. At 25-34~months we reviewed all cases and the strategies which solved them.

RESULTS: Reanalysis of existing ES data alone at two timepoints did not yield new diagnoses. Over the same timeframe, 10 new diagnoses were obtained (17\%) from additional strategies, such as microarray detection of copy number variation, repeat sequencing to improve coverage, and trio sequencing. Twenty-seven peer-reviewed articles were identified on the literature review, with a median new diagnosis rate via reanalysis of 15\% and median reanalysis timeframe of 22~months.

CONCLUSION: Our findings suggest that an interval of greater than 18~months from the original report may be optimal for reanalysis. We also recommend a multi-faceted strategy for cases remaining unsolved after singleton ES.

}, issn = {2324-9269}, doi = {10.1002/mgg3.1508}, author = {Tan, Natalie B and Stapleton, Rachel and Stark, Zornitza and Delatycki, Martin B and Yeung, Alison and Hunter, Matthew F and Amor, David J and Brown, Natasha J and Stutterd, Chloe A and McGillivray, George and Yap, Patrick and Regan, Matthew and Chong, Belinda and Fanjul Fernandez, Miriam and Marum, Justine and Phelan, Dean and Pais, Lynn S and White, Susan M and Lunke, Sebastian and Tan, Tiong Y} } @article {618, title = {Severe neurocognitive and growth disorders due to variation in THOC2, an essential component of nuclear mRNA export machinery.}, journal = {Hum Mutat}, volume = {39}, year = {2018}, month = {2018 08}, pages = {1126-1138}, abstract = {

Highly conserved TREX-mediated mRNA export is emerging as a key pathway in neuronal development and differentiation. TREX subunit variants cause neurodevelopmental disorders (NDDs) by interfering with mRNA export from the cell nucleus to the cytoplasm. Previously we implicated four missense variants in the X-linked THOC2 gene in intellectual disability (ID). We now report an additional six affected individuals from five unrelated families with two de novo and three maternally inherited pathogenic or likely pathogenic variants in THOC2 extending the genotypic and phenotypic spectrum. These comprise three rare missense THOC2 variants that affect evolutionarily conserved amino acid residues and reduce protein stability and two with canonical splice-site THOC2 variants that result in C-terminally truncated THOC2 proteins. We present detailed clinical assessment and functional studies on a de novo variant in a female with an epileptic encephalopathy and discuss an additional four families with rare variants in THOC2 with supportive evidence for pathogenicity. Severe neurocognitive features, including movement and seizure disorders, were observed in this cohort. Taken together our data show that even subtle alterations to the canonical molecular pathways such as mRNA export, otherwise essential for cellular life, can be compatible with life, but lead to NDDs in humans.

}, issn = {1098-1004}, doi = {10.1002/humu.23557}, author = {Kumar, Raman and Gardner, Alison and Homan, Claire C and Douglas, Evelyn and Mefford, Heather and Wieczorek, Dagmar and L{\"u}decke, Hermann-Josef and Stark, Zornitza and Sadedin, Simon and Nowak, Catherine Bearce and Douglas, Jessica and Parsons, Gretchen and Mark, Paul and Loidi, Lourdes and Herman, Gail E and Mihalic Mosher, Theresa and Gillespie, Meredith K and Brady, Lauren and Tarnopolsky, Mark and Madrigal, Irene and Eiris, Jes{\'u}s and Dom{\`e}nech Salgado, Laura and Rabionet, Raquel and Strom, Tim M and Ishihara, Naoko and Inagaki, Hidehito and Kurahashi, Hiroki and Dudding-Byth, Tracy and Palmer, Elizabeth E and Field, Michael and Gecz, Jozef} } @article {610, title = {SYT1-associated neurodevelopmental disorder: a case series.}, journal = {Brain}, volume = {141}, year = {2018}, month = {2018 Sep 01}, pages = {2576-2591}, abstract = {

Synaptotagmin 1 (SYT1) is a critical mediator of fast, synchronous, calcium-dependent neurotransmitter release and also modulates synaptic vesicle endocytosis. This paper describes 11 patients with de novo heterozygous missense mutations in SYT1. All mutations alter highly conserved residues, and cluster in two regions of the SYT1 C2B domain at positions Met303 (M303K), Asp304 (D304G), Asp366 (D366E), Ile368 (I368T) and Asn371 (N371K). Phenotypic features include infantile hypotonia, congenital ophthalmic abnormalities, childhood-onset hyperkinetic movement disorders, motor stereotypies, and developmental delay varying in severity from moderate to profound. Behavioural characteristics include sleep disturbance and episodic agitation. Absence of epileptic seizures and normal orbitofrontal head circumference are important negative features. Structural MRI is unremarkable but EEG disturbance is universal, characterized by intermittent low frequency high amplitude oscillations. The functional impact of these five de novo SYT1 mutations has been assessed by expressing rat SYT1 protein containing the equivalent human variants in wild-type mouse primary hippocampal cultures. All mutant forms of SYT1 were expressed at levels approximately equal to endogenous wild-type protein, and correctly localized to nerve terminals at rest, except for SYT1M303K, which was expressed at a lower level and failed to localize at nerve terminals. Following stimulation, SYT1I368T and SYT1N371K relocalized to nerve terminals at least as efficiently as wild-type SYT1. However, SYT1D304G and SYT1D366E failed to relocalize to nerve terminals following stimulation, indicative of impairments in endocytic retrieval and trafficking of SYT1. In addition, the presence of SYT1 variants at nerve terminals induced a slowing of exocytic rate following sustained action potential stimulation. The extent of disturbance to synaptic vesicle kinetics is mirrored by the severity of the affected individuals{\textquoteright} phenotypes, suggesting that the efficiency of SYT1-mediated neurotransmitter release is critical to cognitive development. In summary, de novo dominant SYT1 missense mutations are associated with a recognizable neurodevelopmental syndrome, and further cases can now be diagnosed based on clinical features, electrophysiological signature and mutation characteristics. Variation in phenotype severity may reflect mutation-specific impact on the diverse physiological functions of SYT1.

}, issn = {1460-2156}, doi = {10.1093/brain/awy209}, author = {Baker, Kate and Gordon, Sarah L and Melland, Holly and Bumbak, Fabian and Scott, Daniel J and Jiang, Tess J and Owen, David and Turner, Bradley J and Boyd, Stewart G and Rossi, Mari and Al-Raqad, Mohammed and Elpeleg, Orly and Peck, Dawn and Mancini, Grazia M S and Wilke, Martina and Zollino, Marcella and Marangi, Giuseppe and Weigand, Heike and Borggraefe, Ingo and Haack, Tobias and Stark, Zornitza and Sadedin, Simon and Tan, Tiong Yang and Jiang, Yunyun and Gibbs, Richard A and Ellingwood, Sara and Amaral, Michelle and Kelley, Whitley and Kurian, Manju A and Cousin, Michael A and Raymond, F Lucy} } @article {633, title = {De novo mutations in HNRNPU result in a neurodevelopmental syndrome.}, journal = {Am J Med Genet A}, volume = {173}, year = {2017}, month = {2017 Nov}, pages = {3003-3012}, abstract = {

Exome sequencing in the context of developmental disorders is a useful technique, but variants found need to be interpreted in the context of detailed phenotypic information. Whole gene deletions and loss-of-function-mutations in the HNRNPU gene have been associated with intellectual disability and seizures in some patients. However, a unifying syndromic phenotype has not been previously elucidated. Here, we report a total of seven patients (six patients identified through the Wellcome Trust Deciphering Developmental Disorders study, with one additional patient), who have heterozygous de novo mutations in HNRNPU. These were found via trio-based exome sequencing. All but one of the mutations is predicted to cause loss-of-function. These patients have dysmorphic features in common, including prominent eyebrows, long palpebral fissures, overhanging columella, and thin upper lip. All patients have developmental delay and intellectual disability (ID), ranging from moderate to severe. Seizures are common from early childhood. These initially occur in the context of febrile episodes. This series demonstrates common phenotypic features, including emerging dysmorphism, associated with heterozygous HNRNPU mutations. This allows us to define a novel neurodevelopmental syndrome, with a likely mechanism of haploinsufficiency.

}, keywords = {Adolescent, Adult, Child, Child, Preschool, Developmental Disabilities, Exome, Female, Genetic Predisposition to Disease, Haploinsufficiency, Heterogeneous-Nuclear Ribonucleoprotein U, Heterozygote, Humans, Infant, Intellectual Disability, Male, Mutation, Neurodevelopmental Disorders, Phenotype, Seizures, Young Adult}, issn = {1552-4833}, doi = {10.1002/ajmg.a.38492}, author = {Yates, T Michael and Vasudevan, Pradeep C and Chandler, Kate E and Donnelly, Deirdre E and Stark, Zornitza and Sadedin, Simon and Willoughby, Josh and Balasubramanian, Meena} } @article {273, title = {Loss-of-function HDAC8 mutations cause a phenotypic spectrum of Cornelia de Lange syndrome-like features, ocular hypertelorism, large fontanelle and X-linked inheritance.}, journal = {Hum Mol Genet}, volume = {23}, year = {2014}, month = {2014 Jun 01}, pages = {2888-900}, abstract = {

Cornelia de Lange syndrome (CdLS) is a multisystem genetic disorder with distinct facies, growth failure, intellectual disability, distal limb anomalies, gastrointestinal and neurological disease. Mutations in NIPBL, encoding a cohesin regulatory protein, account for >80\% of cases with typical facies. Mutations in the core cohesin complex proteins, encoded by the SMC1A, SMC3 and RAD21 genes, together account for \~{}5\% of subjects, often with atypical CdLS features. Recently, we identified mutations in the X-linked gene HDAC8 as the cause of a small number of CdLS cases. Here, we report a cohort of 38 individuals with an emerging spectrum of features caused by HDAC8 mutations. For several individuals, the diagnosis of CdLS was not considered prior to genomic testing. Most mutations identified are missense and de novo. Many cases are heterozygous females, each with marked skewing of X-inactivation in peripheral blood DNA. We also identified eight hemizygous males who are more severely affected. The craniofacial appearance caused by HDAC8 mutations overlaps that of typical CdLS but often displays delayed anterior fontanelle closure, ocular hypertelorism, hooding of the eyelids, a broader nose and dental anomalies, which may be useful discriminating features. HDAC8 encodes the lysine deacetylase for the cohesin subunit SMC3 and analysis of the functional consequences of the missense mutations indicates that all cause a loss of enzymatic function. These data demonstrate that loss-of-function mutations in HDAC8 cause a range of overlapping human developmental phenotypes, including a phenotypically distinct subgroup of CdLS.

}, keywords = {Amino Acid Sequence, Child, Child, Preschool, Cohort Studies, Cranial Fontanelles, De Lange Syndrome, Eye Abnormalities, Female, Genes, X-Linked, Histone Deacetylases, Humans, Hypertelorism, Infant, Male, Molecular Sequence Data, Mutation, Missense, Phenotype, Repressor Proteins, Sequence Alignment}, issn = {1460-2083}, doi = {10.1093/hmg/ddu002}, author = {Kaiser, Frank J and Ansari, Morad and Braunholz, Diana and Concepci{\'o}n Gil-Rodr{\'\i}guez, Mar{\'\i}a and Decroos, Christophe and Wilde, Jonathan J and Fincher, Christopher T and Kaur, Maninder and Bando, Masashige and Amor, David J and Atwal, Paldeep S and Bahlo, Melanie and Bowman, Christine M and Bradley, Jacquelyn J and Brunner, Han G and Clark, Dinah and Del Campo, Miguel and Di Donato, Nataliya and Diakumis, Peter and Dubbs, Holly and Dyment, David A and Eckhold, Juliane and Ernst, Sarah and Ferreira, Jose C and Francey, Lauren J and Gehlken, Ulrike and Guill{\'e}n-Navarro, Encarna and Gyftodimou, Yolanda and Hall, Bryan D and Hennekam, Raoul and Hudgins, Louanne and Hullings, Melanie and Hunter, Jennifer M and Yntema, Helger and Innes, A Micheil and Kline, Antonie D and Krumina, Zita and Lee, Hane and Leppig, Kathleen and Lynch, Sally Ann and Mallozzi, Mark B and Mannini, Linda and McKee, Shane and Mehta, Sarju G and Micule, Ieva and Mohammed, Shehla and Moran, Ellen and Mortier, Geert R and Moser, Joe-Ann S and Noon, Sarah E and Nozaki, Naohito and Nunes, Luis and Pappas, John G and Penney, Lynette S and P{\'e}rez-Ayt{\'e}s, Antonio and Petersen, Michael B and Puisac, Beatriz and Revencu, Nicole and Roeder, Elizabeth and Saitta, Sulagna and Scheuerle, Angela E and Schindeler, Karen L and Siu, Victoria M and Stark, Zornitza and Strom, Samuel P and Thiese, Heidi and Vater, Inga and Willems, Patrick and Williamson, Kathleen and Wilson, Louise C and Hakonarson, Hakon and Quintero-Rivera, Fabiola and Wierzba, Jolanta and Musio, Antonio and Gillessen-Kaesbach, Gabriele and Ramos, Feliciano J and Jackson, Laird G and Shirahige, Katsuhiko and Pi{\'e}, Juan and Christianson, David W and Krantz, Ian D and FitzPatrick, David R and Deardorff, Matthew A} }