Welcome to the CBRG
The Computational Biology Research Group (CBRG) provides computing support for
bioinformatics analysis at the University
of Oxford. We have expertise in many aspects of bioinformatics (sequence analysis, microarrays, proteomics and integration).
We especially encourage collaborations that require writing custom software, bioinformatics tools and databases.
An account with the CBRG has many benefits and gives automatic access to a large number of molecular biology computing packages and
to numerous biological databases.
We are based at the Sir William Dunn School of Pathology and at the
Weatherall Institute of Molecular Medicine. Full details can be found on
the contact details page.
Twigg SR, Hufnagel RB, Miller KA, Zhou Y, McGowan SJ, Taylor J, Craft J, Taylor JC, Santoro SL, Huang T, Hopkin RJ, Brady AF, Clayton-Smith J, Clericuzio CL, Grange DK, Groesser L, Hafner C, Horn D, Temple IK, Dobyns WB, Curry CJ, Jones MC, Wilkie AO
A Recurrent Mosaic Mutation in SMO, Encoding the Hedgehog Signal Transducer Smoothened, Is the Major Cause of Curry-Jones Syndrome.
Am J Hum Genet (2016) 98: 1256-65
» View abstract
Curry-Jones syndrome (CJS) is a multisystem disorder characterized by patchy skin lesions, polysyndactyly, diverse cerebral malformations, unicoronal craniosynostosis, iris colobomas, microphthalmia, and intestinal malrotation with myofibromas or hamartomas. Cerebellar medulloblastoma has been described in a single affected individual; in another, biopsy of skin lesions showed features of trichoblastoma. The combination of asymmetric clinical features, patchy skin manifestations, and neoplastic association previously led to the suggestion that this could be a mosaic condition, possibly involving hedgehog (Hh) signaling. Here, we show that CJS is caused by recurrent somatic mosaicism for a nonsynonymous variant in SMO (c.1234C>T [p.Leu412Phe]), encoding smoothened (SMO), a G-protein-coupled receptor that transduces Hh signaling. We identified eight mutation-positive individuals (two of whom had not been reported previously) with highly similar phenotypes and demonstrated varying amounts of the mutant allele in different tissues. We present detailed findings from brain MRI in three mutation-positive individuals. Somatic SMO mutations that result in constitutive activation have been described in several tumors, including medulloblastoma, ameloblastoma, and basal cell carcinoma. Strikingly, the most common of these mutations is the identical nonsynonymous variant encoding p.Leu412Phe. Furthermore, this substitution has been shown to activate SMO in the absence of Hh signaling, providing an explanation for tumor development in CJS. This raises therapeutic possibilities for using recently generated Hh-pathway inhibitors. In summary, our work uncovers the major genetic cause of CJS and illustrates strategies for gene discovery in the context of low-level tissue-specific somatic mosaicism.
Dolatshad H, Pellagatti A, Liberante FG, Llorian M, Repapi E, Steeples V, Roy S, Scifo L, Armstrong RN, Shaw J, Yip BH, Killick S, KuÅ¡ec R, Taylor S, Mills KI, Savage KI, Smith CW, Boultwood J
Cryptic splicing events in the iron transporter ABCB7 and other key target genes in SF3B1-mutant myelodysplastic syndromes.
Leukemia (2016) :
» View abstract
The splicing factor SF3B1 is the most frequently mutated gene in myelodysplastic syndromes (MDS), and is strongly associated with the presence of ring sideroblasts (RS). We have performed a systematic analysis of cryptic splicing abnormalities from RNA sequencing data on hematopoietic stem cells (HSCs) of SF3B1-mutant MDS cases with RS. Aberrant splicing events in many downstream target genes were identified and cryptic 3' splice site usage was a frequent event in SF3B1-mutant MDS. The iron transporter ABCB7 is a well-recognized candidate gene showing marked downregulation in MDS with RS. Our analysis unveiled aberrant ABCB7 splicing, due to usage of an alternative 3' splice site in MDS patient samples, giving rise to a premature termination codon in the ABCB7 mRNA. Treatment of cultured SF3B1-mutant MDS erythroblasts and a CRISPR/Cas9-generated SF3B1-mutant cell line with the nonsense-mediated decay (NMD) inhibitor cycloheximide showed that the aberrantly spliced ABCB7 transcript is targeted by NMD. We describe cryptic splicing events in the HSCs of SF3B1-mutant MDS, and our data support a model in which NMD-induced downregulation of the iron exporter ABCB7 mRNA transcript resulting from aberrant splicing caused by mutant SF3B1 underlies the increased mitochondrial iron accumulation found in MDS patients with RS.Leukemia advance online publication, 17 June 2016; doi:10.1038/leu.2016.149.
Bannard O, McGowan SJ, Ersching J, Ishido S, Victora GD, Shin JS, Cyster JG
Ubiquitin-mediated fluctuations in MHC class II facilitate efficient germinal center B cell responses.
J Exp Med (2016) 213: 993-1009
» View abstract
Antibody affinity maturation occurs in germinal centers (GCs) through iterative rounds of somatic hypermutation and selection. Selection involves B cells competing for T cell help based on the amount of antigen they capture and present on their MHC class II (MHCII) proteins. How GC B cells are able to rapidly and repeatedly transition between mutating their B cell receptor genes and then being selected shortly after is not known. We report that MHCII surface levels and degradation are dynamically regulated in GC B cells. Through ectopic expression of a photoconvertible MHCII-mKikGR chimeric gene, we found that individual GC B cells differed in the rates of MHCII protein turnover. Fluctuations in surface MHCII levels were dependent on ubiquitination and the E3 ligase March1. Increases in March1 expression in centroblasts correlated with decreases in surface MHCII levels, whereas CD83 expression in centrocytes helped to stabilize MHCII at that stage. Defects in MHCII ubiquitination caused GC B cells to accumulate greater amounts of a specific peptide-MHCII (pMHCII), suggesting that MHCII turnover facilitates the replacement of old complexes. We propose that pMHCII complexes are periodically targeted for degradation in centroblasts to favor the presentation of recently acquired antigens, thereby promoting the fidelity and efficiency of selection.
Goos JA, Fenwick AL, Swagemakers SM, McGowan SJ, Knight SJ, Twigg SR, Hoogeboom AJ, van Dooren MF, Magielsen FJ, Wall SA, Mathijssen IM, Wilkie AO, van der Spek PJ, van den Ouweland AM
Identification of Intragenic Exon Deletions and Duplication of TCF12 by Whole Genome or Targeted Sequencing as a Cause of TCF12-Related Craniosynostosis.
Hum Mutat (2016) 37: 732-6
» View abstract
TCF12-related craniosynostosis can be caused by small heterozygous loss-of-function mutations in TCF12. Large intragenic rearrangements, however, have not been described yet. Here, we present the identification of four large rearrangements in TCF12 causing TCF12-related craniosynostosis. Whole-genome sequencing was applied on the DNA of 18 index cases with coronal synostosis and their family members (43 samples in total). The data were analyzed using an autosomal-dominant disease model. Structural variant analysis reported intragenic exon deletions (of sizes 84.9, 8.6, and 5.4 kb) in TCF12 in three different families. The results were confirmed by deletion-specific PCR and dideoxy-sequence analysis. Separately, targeted sequencing of the TCF12 genomic region in a patient with coronal synostosis identified a tandem duplication of 11.3 kb. The pathogenic effect of this duplication was confirmed by cDNA analysis. These findings indicate the importance of screening for larger rearrangements in patients suspected to have TCF12-related craniosynostosis.
Maher GJ, McGowan SJ, Giannoulatou E, Verrill C, Goriely A, Wilkie AO
Visualizing the origins of selfish de novo mutations in individual seminiferous tubules of human testes.
Proc Natl Acad Sci U S A (2016) 113: 2454-9
» View abstract
De novo point mutations arise predominantly in the male germline and increase in frequency with age, but it has not previously been possible to locate specific, identifiable mutations directly within the seminiferous tubules of human testes. Using microdissection of tubules exhibiting altered expression of the spermatogonial markers MAGEA4, FGFR3, and phospho-AKT, whole genome amplification, and DNA sequencing, we establish an in situ strategy for discovery and analysis of pathogenic de novo mutations. In 14 testes from men aged 39-90 y, we identified 11 distinct gain-of-function mutations in five genes (fibroblast growth factor receptors FGFR2 and FGFR3, tyrosine phosphatase PTPN11, and RAS oncogene homologs HRAS and KRAS) from 16 of 22 tubules analyzed; all mutations have known associations with severe diseases, ranging from congenital or perinatal lethal disorders to somatically acquired cancers. These results support proposed selfish selection of spermatogonial mutations affecting growth factor receptor-RAS signaling, highlight its prevalence in older men, and enable direct visualization of the microscopic anatomy of elongated mutant clones.
Davies JO, Telenius JM, McGowan SJ, Roberts NA, Taylor S, Higgs DR, Hughes JR
Multiplexed analysis of chromosome conformation at vastly improved sensitivity.
Nat Methods (2015) 13: 74-80
» View abstract
Methods for analyzing chromosome conformation in mammalian cells are either low resolution or low throughput and are technically challenging. In next-generation (NG) Capture-C, we have redesigned the Capture-C method to achieve unprecedented levels of sensitivity and reproducibility. NG Capture-C can be used to analyze many genetic loci and samples simultaneously. High-resolution data can be produced with as few as 100,000 cells, and single-nucleotide polymorphisms can be used to generate allele-specific tracks. The method is straightforward to perform and should greatly facilitate the investigation of many questions related to gene regulation as well as the functional dissection of traits examined in genome-wide association studies.
Ramcharan R, Aleksic T, Kamdoum WP, Gao S, Pfister SX, Tanner J, Bridges E, Asher R, Watson AJ, Margison GP, Woodcock M, Repapi E, Li JL, Middleton MR, Macaulay VM
IGF-1R inhibition induces schedule-dependent sensitization of human melanoma to temozolomide.
Oncotarget (2015) 6: 39877-90
» View abstract
Prior studies implicate type 1 IGF receptor (IGF-1R) in mediating chemo-resistance. Here, we investigated whether IGF-1R influences response to temozolomide (TMZ), which generates DNA adducts that are removed by O6-methylguanine-DNA methyltransferase (MGMT), or persist causing replication-associated double-strand breaks (DSBs). Initial assessment in 10 melanoma cell lines revealed that TMZ resistance correlated with MGMT expression (r = 0.79, p = 0.009), and in MGMT-proficient cell lines, with phospho-IGF-1R (r = 0.81, p = 0.038), suggesting that TMZ resistance associates with IGF-1R activation. Next, effects of IGF-1R inhibitors (IGF-1Ri) AZ3801 and linsitinib (OSI-906) were tested on TMZ-sensitivity, cell cycle progression and DSB induction. IGF-1Ri sensitized BRAF wild-type and mutant melanoma cells to TMZ in vitro, an effect that was independent of MGMT. Cells harboring wild-type p53 were more sensitive to IGF-1Ri, and showed schedule-dependent chemo-sensitization that was most effective when IGF-1Ri followed TMZ. This sequence sensitized to clinically-achievable TMZ concentrations and enhanced TMZ-induced apoptosis. Simultaneous or prior IGF-1Ri caused less effective chemo-sensitization, associated with increased G1 population and reduced accumulation of TMZ-induced DSBs. Clinically relevant sequential (TMZ â†’ IGF-1Ri) treatment was tested in mice bearing A375M (V600E BRAF, wild-type p53) melanoma xenografts, achieving peak plasma/tumor IGF-1Ri levels comparable to clinical Cmax, and inducing extensive intratumoral apoptosis. TMZ or IGF-1Ri caused minor inhibition of tumor growth (gradient reduction 13%, 25% respectively), while combination treatment caused supra-additive growth delay (72%) that was significantly different from control (p < 0.01), TMZ (p < 0.01) and IGF-1Ri (p < 0.05) groups. These data highlight the importance of scheduling when combining IGF-1Ri and other targeted agents with drugs that induce replication-associated DNA damage.
Twigg SR, Forecki J, Goos JA, Richardson IC, Hoogeboom AJ, van den Ouweland AM, Swagemakers SM, Lequin MH, Van Antwerp D, McGowan SJ, Westbury I, Miller KA, Wall SA, van der Spek PJ, Mathijssen IM, Pauws E, Merzdorf CS, Wilkie AO
Gain-of-Function Mutations in ZIC1 Are Associated with Coronal Craniosynostosis and Learning Disability.
Am J Hum Genet (2015) 97: 378-88
» View abstract
Human ZIC1 (zinc finger protein of cerebellum 1), one of five homologs of the Drosophila pair-rule gene odd-paired, encodes a transcription factor previously implicated in vertebrate brain development. Heterozygous deletions of ZIC1 and its nearby paralog ZIC4 on chromosome 3q25.1 are associated with Dandy-Walker malformation of the cerebellum, and loss of the orthologous Zic1 gene in the mouse causes cerebellar hypoplasia and vertebral defects. We describe individuals from five families with heterozygous mutations located in the final (third) exon of ZIC1 (encoding four nonsense and one missense change) who have a distinct phenotype in which severe craniosynostosis, specifically involving the coronal sutures, and variable learning disability are the most characteristic features. The location of the nonsense mutations predicts escape of mutant ZIC1 transcripts from nonsense-mediated decay, which was confirmed in a cell line from an affected individual. Both nonsense and missense mutations are associated with altered and/or enhanced expression of a target gene, engrailed-2, in a Xenopus embryo assay. Analysis of mouse embryos revealed a localized domain of Zic1 expression at embryonic days 11.5-12.5 in a region overlapping the supraorbital regulatory center, which patterns the coronal suture. We conclude that the human mutations uncover a previously unsuspected role for Zic1 in early cranial suture development, potentially by regulating engrailed 1, which was previously shown to be critical for positioning of the murine coronal suture. The diagnosis of a ZIC1 mutation has significant implications for prognosis and we recommend genetic testing when common causes of coronal synostosis have been excluded.
Ledaki I, McIntyre A, Wigfield S, Buffa F, McGowan S, Baban D, Li JL, Harris AL
Carbonic anhydrase IX induction defines a heterogeneous cancer cell response to hypoxia and mediates stem cell-like properties and sensitivity to HDAC inhibition.
Oncotarget (2015) 6: 19413-27
» View abstract
Carbonic anhydrase IX (CAIX) is strongly induced by hypoxia and its overexpression is associated with poor therapeutic outcome in cancer. Here, we report that hypoxia promotes tumour heterogeneity through the epigenetic regulation of CAIX. Based on hypoxic CAIX expression we identify and characterize two distinct populations of tumour cells, one that has inducible expression of CAIX and one that does not. The CAIX+ve population is enriched with cells expressing cancer stem cell markers and which have high self-renewal capacity. We show that differential CAIX expression is due to differences in chromatin structure. To further investigate the relationship between chromatin organization and hypoxic induction of CAIX expression we investigated the effect of JQ1 an inhibitor of BET bromodomain proteins and A366 a selective inhibitor of the H3K9 methyltransferase G9a/GLP. We identified that these drugs were able to modulate hypoxic CAIX expression induction. This further highlights the role of epigenetic modification in adaption to hypoxia and also in regulation of heterogeneity of cells within tumours. Interestingly, we identified that the two subpopulations show a differential sensitivity to HDAC inhibitors, NaBu or SAHA, with the CAIX positive showing greater sensitivity to treatment. We propose that drugs modulating chromatin regulation of expression may be used to reduce heterogeneity induced by hypoxia and could in combination have significant clinical consequences.
Clynes D, Jelinska C, Xella B, Ayyub H, Scott C, Mitson M, Taylor S, Higgs DR, Gibbons RJ
Suppression of the alternative lengthening of telomere pathway by the chromatin remodelling factor ATRX.
Nat Commun (2015) 6: 7538
» View abstract
Fifteen per cent of cancers maintain telomere length independently of telomerase by the homologous recombination (HR)-associated alternative lengthening of telomeres (ALT) pathway. A unifying feature of these tumours are mutations in ATRX. Here we show that expression of ectopic ATRX triggers a suppression of the pathway and telomere shortening. Importantly ATRX-mediated ALT suppression is dependent on the histone chaperone DAXX. Re-expression of ATRX is associated with a reduction in replication fork stalling, a known trigger for HR and loss of MRN from telomeres. A G-quadruplex stabilizer partially reverses the effect of ATRX, inferring ATRX may normally facilitate replication through these sequences that, if they persist, promote ALT. We propose that defective telomere chromatinization through loss of ATRX promotes the persistence of aberrant DNA secondary structures, which in turn present a barrier to DNA replication, leading to replication fork stalling, collapse, HR and subsequent recombination-mediated telomere synthesis in ALT cancers.
Belaya K, Rodríguez Cruz PM, Liu WW, Maxwell S, McGowan S, Farrugia ME, Petty R, Walls TJ, Sedghi M, Basiri K, Yue WW, Sarkozy A, Bertoli M, Pitt M, Kennett R, Schaefer A, Bushby K, Parton M, Lochmüller H, Palace J, Muntoni F, Beeson D
Mutations in GMPPB cause congenital myasthenic syndrome and bridge myasthenic disorders with dystroglycanopathies.
Brain (2015) 138: 2493-504
» View abstract
Congenital myasthenic syndromes are inherited disorders that arise from impaired signal transmission at the neuromuscular junction. Mutations in at least 20 genes are known to lead to the onset of these conditions. Four of these, ALG2, ALG14, DPAGT1 and GFPT1, are involved in glycosylation. Here we identify a fifth glycosylation gene, GMPPB, where mutations cause congenital myasthenic syndrome. First, we identified recessive mutations in seven cases from five kinships defined as congenital myasthenic syndrome using decrement of compound muscle action potentials on repetitive nerve stimulation on electromyography. The mutations were present through the length of the GMPPB, and segregation, in silico analysis, exon trapping, cell transfection followed by western blots and immunostaining were used to determine pathogenicity. GMPPB congenital myasthenic syndrome cases show clinical features characteristic of congenital myasthenic syndrome subtypes that are due to defective glycosylation, with variable weakness of proximal limb muscle groups while facial and eye muscles are largely spared. However, patients with GMPPB congenital myasthenic syndrome had more prominent myopathic features that were detectable on muscle biopsies, electromyography, muscle magnetic resonance imaging, and through elevated serum creatine kinase levels. Mutations in GMPPB have recently been reported to lead to the onset of muscular dystrophy dystroglycanopathy. Analysis of four additional GMPPB-associated muscular dystrophy dystroglycanopathy cases by electromyography found that a defective neuromuscular junction component is not always present. Thus, we find mutations in GMPPB can lead to a wide spectrum of clinical features where deficit in neuromuscular transmission is the major component in a subset of cases. Clinical recognition of GMPPB-associated congenital myasthenic syndrome may be complicated by the presence of myopathic features, but correct diagnosis is important because affected individuals can respond to appropriate treatments.
Taylor JC, Martin HC, Lise S, Broxholme J, Cazier JB, Rimmer A, Kanapin A, Lunter G, Fiddy S, Allan C, Aricescu AR, Attar M, Babbs C, Becq J, Beeson D, Bento C, Bignell P, Blair E, Buckle VJ, Bull K, Cais O, Cario H, Chapel H, Copley RR, Cornall R, Craft J, Dahan K, Davenport EE, Dendrou C, Devuyst O, Fenwick AL, Flint J, Fugger L, Gilbert RD, Goriely A, Green A, Greger IH, Grocock R, Gruszczyk AV, Hastings R, Hatton E, Higgs D, Hill A, Holmes C, Howard M, Hughes L, Humburg P, Johnson D, Karpe F, Kingsbury Z, Kini U, Knight JC, Krohn J, Lamble S, Langman C, Lonie L, Luck J, McCarthy D, McGowan SJ, McMullin MF, Miller KA, Murray L, Németh AH, Nesbit MA, Nutt D, Ormondroyd E, Oturai AB, Pagnamenta A, Patel SY, Percy M, Petousi N, Piazza P, Piret SE, Polanco-Echeverry G, Popitsch N, Powrie F, Pugh C, Quek L, Robbins PA, Robson K, Russo A, Sahgal N, van Schouwenburg PA, Schuh A, Silverman E, Simmons A, Sørensen PS, Sweeney E, Taylor J, Thakker RV, Tomlinson I, Trebes A, Twigg SR, Uhlig HH, Vyas P, Vyse T, Wall SA, Watkins H, Whyte MP, Witty L, Wright B, Yau C, Buck D, Humphray S, Ratcliffe PJ, Bell JI, Wilkie AO, Bentley D, Donnelly P, McVean G
Factors influencing success of clinical genome sequencing across a broad spectrum of disorders.
Nat Genet (2015) 47: 717-26
» View abstract
To assess factors influencing the success of whole-genome sequencing for mainstream clinical diagnosis, we sequenced 217 individuals from 156 independent cases or families across a broad spectrum of disorders in whom previous screening had identified no pathogenic variants. We quantified the number of candidate variants identified using different strategies for variant calling, filtering, annotation and prioritization. We found that jointly calling variants across samples, filtering against both local and external databases, deploying multiple annotation tools and using familial transmission above biological plausibility contributed to accuracy. Overall, we identified disease-causing variants in 21% of cases, with the proportion increasing to 34% (23/68) for mendelian disorders and 57% (8/14) in family trios. We also discovered 32 potentially clinically actionable variants in 18 genes unrelated to the referral disorder, although only 4 were ultimately considered reportable. Our results demonstrate the value of genome sequencing for routine clinical diagnosis but also highlight many outstanding challenges.
Zhang Y, Makvandi-Nejad S, Qin L, Zhao Y, Zhang T, Wang L, Repapi E, Taylor S, McMichael A, Li N, Dong T, Wu H
Interferon-induced transmembrane protein-3 rs12252-C is associated with rapid progression of acute HIV-1 infection in Chinese MSM cohort.
AIDS (2015) 29: 889-94
» View abstract
The interferon-inducible transmembrane protein-3 (IFITM3) is a protein that restricts multiple pathogenic viruses such as influenza virus. The single-nucleotide polymorphism rs12252-C, which is rare in Caucasian populations, but much more common in the Han Chinese population, has been found in much higher homozygous frequency in patients with severe acute influenza. Until now, there has been no study on the effect of this genetic variant on the clinical control of other viral infections.To investigate the impact of IFITM3-rs12252 genotypes on primary HIV-1 infection progression in an acute HIV-1-infected cohort in Beijing (PRIMO), China.We identified IFITM3-rs12252 genotypes of 178 acute HIV-1-infected patients and 196 HIV-negative candidates from the PRIMO cohort. HIV-1 viral load and CD4(+) T-cell counts were monitored at multiple time points during the first year of infection, and the association between IFITM3-rs12252 genotype and disease progression was evaluated.The current study shows that the IFITM3-rs12252 genetic variant affects the progression of HIV-1 infection, but not the acquisition. A significantly higher frequency of the CC/CT genotypes was found in rapid progressors compared to nonprogressors. Patients with CC/CT genotypes showed an elevated peak viremia level and significantly lower CD4(+) T-cell count at multiple time points during the first year of primary infection, and a significantly higher risk of rapid decline of the CD4(+) T-cell count to below 350â€Š cells/Î¼l.A novel association between IFITM3 gene polymorphism and rapid disease progression is reported in an acute HIV-1-infected MSM cohort in China.
French A, Yang CT, Taylor S, Watt SM, Carpenter L
Human induced pluripotent stem cell-derived B lymphocytes express sIgM and can be generated via a hemogenic endothelium intermediate.
Stem Cells Dev (2015) 24: 1082-95
» View abstract
The differentiation of human pluripotent stem cells to the B-cell lymphoid lineage has important clinical applications that include in vitro modeling of developmental lymphogenesis in health and disease. Here, we first demonstrate the capacity of human induced pluripotent stem cells (hiPSCs) to differentiate into CD144(+)CD73(-)CD43/CD235a(-) cells, characterized as hemogenic endothelium, and show that this population is capable of differentiating to CD10(+)CD19(+) B lymphocytes. We also demonstrate that B lymphocytes generated from hiPSCs are able to undergo full VDJ rearrangement and express surface IgM (sIgM(+)), thus representing an immature B-cell subset. Efficiency of sIgM expression on the hiPSC-derived B lymphocytes (âˆ¼ 5% of CD19(+) cells) was comparable with B lymphocytes generated from human umbilical cord blood (UCB) hematopoietic progenitor cells. Importantly, when assessed by global transcriptional profiling, hiPSC-derived B-cells show a very high level of similarity when compared with their UCB-derived counterparts, such that from more than 47,000 different transcripts, only 45 were significantly different (with a criteria adjusted P value P<0.05, log FC >1.5 or 2.8-fold). This represents a unique in vitro model to delineate critical events during lymphogeneisis in development and lymphoid diseases such as acute lymphocytic leukemia.
Babbs C, Lloyd D, Pagnamenta AT, Twigg SR, Green J, McGowan SJ, Mirza G, Naples R, Sharma VP, Volpi EV, Buckle VJ, Wall SA, Knight SJ, Parr JR, Wilkie AO
De novo and rare inherited mutations implicate the transcriptional coregulator TCF20/SPBP in autism spectrum disorder.
J Med Genet (2014) 51: 737-47
» View abstract
Autism spectrum disorders (ASDs) are common and have a strong genetic basis, yet the cause of âˆ¼70-80% ASDs remains unknown. By clinical cytogenetic testing, we identified a family in which two brothers had ASD, mild intellectual disability and a chromosome 22 pericentric inversion, not detected in either parent, indicating de novo mutation with parental germinal mosaicism. We hypothesised that the rearrangement was causative of their ASD and localised the chromosome 22 breakpoints.The rearrangement was characterised using fluorescence in situ hybridisation, Southern blotting, inverse PCR and dideoxy-sequencing. Open reading frames and intron/exon boundaries of the two physically disrupted genes identified, TCF20 and TNRC6B, were sequenced in 342 families (260 multiplex and 82 simplex) ascertained by the International Molecular Genetic Study of Autism Consortium (IMGSAC).IMGSAC family screening identified a de novo missense mutation of TCF20 in a single case and significant association of a different missense mutation of TCF20 with ASD in three further families. Through exome sequencing in another project, we independently identified a de novo frameshifting mutation of TCF20 in a woman with ASD and moderate intellectual disability. We did not identify a significant association of TNRC6B mutations with ASD.TCF20 encodes a transcriptional coregulator (also termed SPBP) that is structurally and functionally related to RAI1, the critical dosage-sensitive protein implicated in the behavioural phenotypes of the Smith-Magenis and Potocki-Lupski 17p11.2 deletion/duplication syndromes, in which ASD is frequently diagnosed. This study provides the first evidence that mutations in TCF20 are also associated with ASD.