Complex interaction between HNRNPD mutations and risk polymorphisms is associated with discordant Crohn's disease in monozygotic twins.

Autoimmunity. 2017 Mar 16;:1-2

Authors: Prakash T, Veerappa A, B Ramachandra N

Abstract
Crohn's disease (CD) is a chronic inflammatory bowel disease (IBD) affecting the lining of digestive tracts of the colon and ileum. To investigate the reasons behind the presence of CD phenotype in one of the monozygotic (MZ) twins, we utilized the whole exome sequence (WES) datasets of CD tissue biopsy and CD blood of affected twin and the exome dataset of blood from healthy twin. We report the presence of discordant and rare damaging mutation in HNRNPD and other risk polymorphisms such as, rs12103, rs2241880, rs3810936, rs7076156, rs1042058 and rs1292053. HNRNPD was found carrying two novel heterozygous mutations - a stop gain mutation that truncated the protein at 249th and 268th amino acid position and a single base missense mutation replacing Aspartate with Valine at 300th amino acid. The identified risk polymorphisms were found conferring susceptibility to CD and IBD. Discordant deleterious and damaging mutation was detected in HNRNPD that have been implicated in inflammatory pathways. Integrating these variants led to the elucidation of pathophysiology of CD in the affected twin involving the causal processes of macrophage activation, tissue death, autophagy, immune response, cell-migration and T-cell activation.

PMID: 28300425 [PubMed - as supplied by publisher]

Screening of gene mutations associated with bone metastasis in nonsmall cell lung cancer.

J Cancer Res Ther. 2016 Dec;12(Supplement):C186-C190

Authors: Zhang K, Zhang M, Zhu J, Hong W

Abstract
OBJECTIVE: The objective of this study is to assess the gene mutation of advanced nonsmall cell lung cancer (NSCLC) patients with bone metastasis using next-generation sequencing (NGS), and screen for the driver genes which are associated with bone metastasis of lung cancer.
MATERIALS AND METHODS: Eight clinicopathologic samples from advanced NSCLC combined with bone metastasis patients were collected. Exome sequencing was conducted within 483 tumor-associated genes using Hiseq 2000_PE75 NGS platform.
RESULTS: Three thousand six hundred and twenty gene mutations were identified, including point mutation, insertion, and deletion. Among all genes associated with lung cancer signaling pathways, fibroblast growth factor receptor (FGFR), and cyclin-dependent kinase 12 (CDK12) were found to be mutated in all eight patients. The top three genes were FGFR, ataxia telangiectasia mutated, and CDK12, according to mutation frequency. In the meanwhile, hepatocyte nuclear factor 1 alpha, adenomatous polyposis coli, and CD22 were found to be mutated in all eight patients with an over 50% mutation frequency (75%, 62.5%, and 50%, respectively), which would be the most potential genes accounting for bone metastasis in lung cancer patients.
CONCLUSION: Our findings shed light on several important signalling pathways involved in NSCLC, and suggest new potential molecular targets for treatment of NSCLC patients with bone metastasis.

PMID: 28230015 [PubMed - indexed for MEDLINE]

GRIN3B missense mutation as an inherited risk factor for schizophrenia: whole-exome sequencing in a family with a familiar history of psychotic disorders.

Genet Res (Camb). 2017 01 30;99:e1

Authors: Hornig T, Grüning B, Kundu K, Houwaart T, Backofen R, Biber K, Normann C

Abstract
Glutamate is the most important excitatory neurotransmitter in the brain. The N-methyl-D-aspartate (NMDA) receptor is a glutamate-gated ionotropic cation channel that is composed of several subunits and modulated by a glycine binding site. Many forms of synaptic plasticity depend on the influx of calcium ions through NMDA receptors, and NMDA receptor dysfunction has been linked to a number of neuropsychiatric disorders, including schizophrenia. Whole-exome sequencing was performed in a family with a strong history of psychotic disorders over three generations. We used an iterative strategy to obtain condense and meaningful variants. In this highly affected family, we found a frameshift mutation (rs10666583) in the GRIN3B gene, which codes for the GluN3B subunit of the NMDA receptor in all family members with a psychotic disorder, but not in the healthy relatives. Matsuno et al., also reported this null variant as a risk factor for schizophrenia in 2015. In a broader sample of 22 patients with psychosis, the allele frequency of the rs10666583 mutation variant was increased compared to those of healthy population samples and unaffected relatives. Compared to the 1000 Genomes Project population, we found a significant increase of this variant with a large effect size among patients. The amino acid shift degrades the S1/S2 glycine binding domain of the dominant modulatory GluN3B subunit of the NMDA receptor, which subsequently affects the permeability of the channel pore to calcium ions. A decreased glycine affinity for the GluN3B subunit might cause impaired functional capability of the NMDA receptor and could be an important risk factor for the pathogenesis of psychotic disorders.

PMID: 28132660 [PubMed - indexed for MEDLINE]

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Mutations in the Spliceosome Component CWC27 Cause Retinal Degeneration with or without Additional Developmental Anomalies.

Am J Hum Genet. 2017 Mar 06;:

Authors: Xu M, Xie YA, Abouzeid H, Gordon CT, Fiorentino A, Sun Z, Lehman A, Osman IS, Dharmat R, Riveiro-Alvarez R, Bapst-Wicht L, Babino D, Arno G, Busetto V, Zhao L, Li H, Lopez-Martinez MA, Azevedo LF, Hubert L, Pontikos N, Eblimit A, Lorda-Sanchez I, Kheir V, Plagnol V, Oufadem M, Soens ZT, Yang L, Bole-Feysot C, Pfundt R, Allaman-Pillet N, Nitschké P, Cheetham ME, Lyonnet S, Agrawal SA, Li H, Pinton G, Michaelides M, Besmond C, Li Y, Yuan Z, von Lintig J, Webster AR, Le Hir H, Stoilov P, UK Inherited Retinal Dystrophy Consortium, Amiel J, Hardcastle AJ, Ayuso C, Sui R, Chen R, Allikmets R, Schorderet DF

Abstract
Pre-mRNA splicing factors play a fundamental role in regulating transcript diversity both temporally and spatially. Genetic defects in several spliceosome components have been linked to a set of non-overlapping spliceosomopathy phenotypes in humans, among which skeletal developmental defects and non-syndromic retinitis pigmentosa (RP) are frequent findings. Here we report that defects in spliceosome-associated protein CWC27 are associated with a spectrum of disease phenotypes ranging from isolated RP to severe syndromic forms. By whole-exome sequencing, recessive protein-truncating mutations in CWC27 were found in seven unrelated families that show a range of clinical phenotypes, including retinal degeneration, brachydactyly, craniofacial abnormalities, short stature, and neurological defects. Remarkably, variable expressivity of the human phenotype can be recapitulated in Cwc27 mutant mouse models, with significant embryonic lethality and severe phenotypes in the complete knockout mice while mice with a partial loss-of-function allele mimic the isolated retinal degeneration phenotype. Our study describes a retinal dystrophy-related phenotype spectrum as well as its genetic etiology and highlights the complexity of the spliceosomal gene network.

PMID: 28285769 [PubMed - as supplied by publisher]

Diagnosis with Multiple Epiphyseal Dysplasia Using Whole-exome Sequencing in a Chinese Family.

Chin Med J (Engl). 2017 5th Jan 2017;130(1):104-107

Authors: Liu HY, Xiao JF, Huang J, Wang Y, Wu D, Li T, Wang HD, Guo LJ, Guo QN, Xiao H, Lyu X, Yu ZH

PMID: 28051032 [PubMed - indexed for MEDLINE]

Generation of a novel, multi-stage, progressive, and transplantable model of plasma cell neoplasms.

Sci Rep. 2016 Mar 10;6:22760

Authors: Asai T, Hatlen MA, Lossos C, Ndiaye-Lobry D, Deblasio A, Murata K, Fleisher M, Cortizas EM, Verdun RE, Petrini J, Nimer SD

Abstract
Multiple myeloma is a plasma cell neoplasm with an extremely variable clinical course. Animal models are needed to better understand its pathophysiology and for preclinical testing of potential therapeutic agents. Hematopoietic cells expressing the hypermorphic Rad50(s) allele show hematopoietic failure, which can be mitigated by the lack of a transcription factor, Mef/Elf4. However, we find that 70% of Mef(-/-)Rad50(s/s) mice die from multiple myeloma or other plasma cell neoplasms. These mice initially show an abnormal plasma cell proliferation and monoclonal protein production, and then develop anemia and a decreased bone mineral density. Tumor cells can be serially transplanted and according to array CGH and whole exome sequencing, the pathogenesis of plasma cell neoplasms in these mice is not linked to activation of a specific oncogene, or inactivation of a specific tumor suppressor. This model recapitulates the systemic manifestations of human plasma cell neoplasms, and implicates cooperativity between the Rad50(s) and Mef/Elf4 pathways in initiating myelomagenic mutations that promote plasma cell transformation.

PMID: 26961797 [PubMed - indexed for MEDLINE]

Exome sequencing identified a novel SMAD2 mutation in a Chinese family with early onset aortic aneurysms.

Clin Chim Acta. 2017 Mar 07;:

Authors: Zhang W, Zeng Q, Xu Y, Ying H, Zhou W, Cao Q, Zhou W

Abstract
Aortic aneurysm remains a devastating disease due to its fatal complications, such as aortic dissection and rupture. A subset of aortic aneurysm is caused by genetic defect and to date more than a dozen of disease-causing genes have been discovered to account for the disease. In this study, by using whole exome sequencing, we identified a novel heterozygous missense mutation (c.833C>T, p.A278V) in the SMAD2 gene in a family with early onset aortic aneurysms. The mutation segregated in this family, was high conserved among species and predicted to be pathogenic by multiple in silico programs. To our knowledge, this is the second report that link the SMAD2 mutations to aortic aneurysm. We recommend that SMAD2 should be included in the expanding panel of genetic testing for patients with unexplained aortic aneurysms, which will facilitate genotype-phenotype correlation of SMAD2 mutations. Given the current wide application of molecular diagnosis in clinical setting, identification of the defected gene allows recognition of additional family members at risk for aortic diseases and gene-based management of the carriers.

PMID: 28283438 [PubMed - as supplied by publisher]

Contribution of Mutations in Known Mendelian Glaucoma Genes to Advanced Early-Onset Primary Open-Angle Glaucoma.

Invest Ophthalmol Vis Sci. 2017 Mar 01;58(3):1537-1544

Authors: Zhou T, Souzeau E, Siggs OM, Landers J, Mills R, Goldberg I, Healey PR, Graham S, Hewitt AW, Mackey DA, Galanopoulos A, Casson RJ, Ruddle JB, Ellis J, Leo P, Brown MA, MacGregor S, Sharma S, Burdon KP, Craig JE

Abstract
Purpose: Primary open-angle glaucoma (POAG) and primary congenital glaucoma (PCG) with Mendelian inheritance are caused by mutations in at least nine genes. Utilizing whole-exome sequencing, we examined the disease burden accounted for by these known Mendelian glaucoma genes in a cohort of individuals with advanced early-onset POAG.
Methods: The cases exhibited advanced POAG with young age of diagnosis. Cases and examined local controls were subjected to whole-exome sequencing. Nine hundred ninety-three previously sequenced exomes of Australian controls were called jointly with our dataset. Qualifying variants were selected based on predicted pathogenicity and rarity in public domain gene variant databases. Case-control mutational burdens were calculated for glaucoma-linked genes.
Results: Two hundred eighteen unrelated POAG participants and 103 nonglaucomatous controls were included in addition to 993 unexamined controls. Fifty-eight participants (26.6%) harbored rare potentially pathogenic variants in known glaucoma genes. Enrichment of qualifying variants toward glaucoma was present in all genes except WDR36, in which controls harbored more variants, and TBK1, in which no qualifying variants were detected in cases or controls. After multiple testing correction, only MYOC showed statistically significant enrichment of qualifying variants (odds ratio [OR] = 16.62, P = 6.31×10-16).
Conclusions: Rare, potentially disease-causing variants in Mendelian POAG genes that showed enrichment in our dataset were found in 22.9% of advanced early-onset POAG cases. MYOC variants represented the largest monogenic cause in POAG. The association between WDR36 and POAG was not supported, and the majority of POAG cases did not harbor a potentially disease-causing variant in the remaining Mendelian genes.

PMID: 28282485 [PubMed - in process]

A De Novo Nonsense Mutation in MAGEL2 in a Patient Initially Diagnosed as Opitz-C: Similarities Between Schaaf-Yang and Opitz-C Syndromes.

Sci Rep. 2017 Mar 10;7:44138

Authors: Urreizti R, Cueto-Gonzalez AM, Franco-Valls H, Mort-Farre S, Roca-Ayats N, Ponomarenko J, Cozzuto L, Company C, Bosio M, Ossowski S, Montfort M, Hecht J, Tizzano EF, Cormand B, Vilageliu L, Opitz JM, Neri G, Grinberg D, Balcells S

Abstract
Opitz trigonocephaly C syndrome (OTCS) is a rare genetic disorder characterized by craniofacial anomalies, variable intellectual and psychomotor disability, and variable cardiac defects with a high mortality rate. Different patterns of inheritance and genetic heterogeneity are known in this syndrome. Whole exome and genome sequencing of a 19-year-old girl (P7), initially diagnosed with OTCS, revealed a de novo nonsense mutation, p.Q638*, in the MAGEL2 gene. MAGEL2 is an imprinted, maternally silenced, gene located at 15q11-13, within the Prader-Willi region. Patient P7 carried the mutation in the paternal chromosome. Recently, mutations in MAGEL2 have been described in Schaaf-Yang syndrome (SHFYNG) and in severe arthrogryposis. Patient P7 bears resemblances with SHFYNG cases but has other findings not described in this syndrome and common in OTCS. We sequenced MAGEL2 in nine additional OTCS patients and no mutations were found. This study provides the first clear molecular genetic basis for an OTCS case, indicates that there is overlap between OTCS and SHFYNG syndromes, and confirms that OTCS is genetically heterogeneous. Genes encoding MAGEL2 partners, either in the retrograde transport or in the ubiquitination-deubiquitination complexes, are promising candidates as OTCS disease-causing genes.

PMID: 28281571 [PubMed - in process]

Novel and known ribosomal causes of Diamond-Blackfan anaemia identified through comprehensive genomic characterisation.

J Med Genet. 2017 Mar 09;:

Authors: Mirabello L, Khincha PP, Ellis SR, Giri N, Brodie S, Chandrasekharappa SC, Donovan FX, Zhou W, Hicks BD, Boland JF, Yeager M, Jones K, Zhu B, Wang M, Alter BP, Savage SA

Abstract
BACKGROUND: Diamond-Blackfan anaemia (DBA) is an inherited bone marrow failure syndrome (IBMFS) characterised by erythroid hypoplasia. It is associated with congenital anomalies and a high risk of developing specific cancers. DBA is caused predominantly by autosomal dominant pathogenic variants in at least 15 genes affecting ribosomal biogenesis and function. Two X-linked recessive genes have been identified.
OBJECTIVES: We aim to identify the genetic aetiology of DBA.
METHODS: Of 87 families with DBA enrolled in an institutional review board-approved cohort study (ClinicalTrials.gov Identifier:NCT00027274), 61 had genetic testing information available. Thirty-five families did not have a known genetic cause and thus underwent comprehensive genomic evaluation with whole exome sequencing, deletion and CNV analyses to identify their disease-associated pathogenic variant. Controls for functional studies were healthy mutation-negative individuals enrolled in the same study.
RESULTS: Our analyses uncovered heterozygous pathogenic variants in two previously undescribed genes in two families. One family had a non-synonymous variant (p.K77N) in RPL35; the second family had a non-synonymous variant (p. L51S) in RPL18. Both of these variants result in pre-rRNA processing defects. We identified heterozygous pathogenic variants in previously known DBA genes in 16 of 35 families. Seventeen families who underwent genetic analyses are yet to have a genetic cause of disease identified.
CONCLUSIONS: Overall, heterozygous pathogenic variants in ribosomal genes were identified in 44 of the 61 families (7 2%). De novo pathogenic variants were observed in 57% of patients with DBA. Ongoing studies of DBA genomics will be important to understand this complex disorder.

PMID: 28280134 [PubMed - as supplied by publisher]

Identification of Cadherin 2 (CDH2) Mutations in Arrhythmogenic Right Ventricular Cardiomyopathy.

Circ Cardiovasc Genet. 2017 Apr;10(2):

Authors: Mayosi BM, Fish M, Shaboodien G, Mastantuono E, Kraus S, Wieland T, Kotta MC, Chin A, Laing N, Ntusi NB, Chong M, Horsfall C, Pimstone SN, Gentilini D, Parati G, Strom TM, Meitinger T, Pare G, Schwartz PJ, Crotti L

Abstract
BACKGROUND: Arrhythmogenic right ventricular cardiomyopathy (ARVC) is a genetically heterogeneous condition caused by mutations in genes encoding desmosomal proteins in up to 60% of cases. The 40% of genotype-negative cases point to the need of identifying novel genetic substrates by studying genotype-negative ARVC families.
METHODS AND RESULTS: Whole exome sequencing was performed on 2 cousins with ARVC. Validation of 13 heterozygous variants that survived internal quality and frequency filters was performed by Sanger sequencing. These variants were also genotyped in all family members to establish genotype-phenotype cosegregation. High-resolution melting analysis followed by Sanger sequencing was used to screen for mutations in cadherin 2 (CDH2) gene in unrelated genotype-negative patients with ARVC. In a 3-generation family, we identified by whole exome sequencing a novel mutation in CDH2 (c.686A>C, p.Gln229Pro) that cosegregated with ARVC in affected family members. The CDH2 c.686A>C variant was not present in >200 000 chromosomes available through public databases, which changes a conserved amino acid of cadherin 2 protein and is supported as the causal mutation by parametric linkage analysis. We subsequently screened 73 genotype-negative ARVC probands tested previously for mutations in known ARVC genes and found an additional likely pathogenic variant in CDH2 (c.1219G>A, p.Asp407Asn). CDH2 encodes cadherin 2 (also known as N-cadherin), a protein that plays a vital role in cell adhesion, making it a biologically plausible candidate gene in ARVC pathogenesis.
CONCLUSIONS: These data implicate CDH2 mutations as novel genetic causes of ARVC and contribute to a more complete identification of disease genes involved in cardiomyopathy.

PMID: 28280076 [PubMed - in process]

Loss-of-function Mutation in PMVK Causes Autosomal Dominant Disseminated Superficial Porokeratosis.

Sci Rep. 2016 Apr 07;6:24226

Authors: Wang J, Liu Y, Liu F, Huang C, Han S, Lv Y, Liu CJ, Zhang S, Qin Y, Ling L, Gao M, Yu S, Li C, Huang M, Liao S, Hu X, Lu Z, Liu X, Jiang T, Tang Z, Zhang H, Guo AY, Liu M

Abstract
Disseminated superficial porokeratosis (DSP) is a rare keratinization disorder of the epidermis. It is characterized by keratotic lesions with an atrophic center encircled by a prominent peripheral ridge. We investigated the genetic basis of DSP in two five-generation Chinese families with members diagnosed with DSP. By whole-exome sequencing, we sequencing identified a nonsense variation c.412C > T (p.Arg138*) in the phosphomevalonate kinase gene (PMVK), which encodes a cytoplasmic enzyme catalyzing the conversion of mevalonate 5-phosphate to mevalonate 5-diphosphate in the mevalonate pathway. By co-segregation and haplotype analyses as well as exclusion testing of 500 normal control subjects, we demonstrated that this genetic variant was involved in the development of DSP in both families. We obtained further evidence from studies using HaCaT cells as models that this variant disturbed subcellular localization, expression and solubility of PMVK. We also observed apparent apoptosis in and under the cornoid lamella of PMVK-deficient lesional tissues, with incomplete differentiation of keratinocytes. Our findings suggest that PMVK is a potential novel gene involved in the pathogenesis of DSP and PMVK deficiency or abnormal keratinocyte apoptosis could lead to porokeratosis.

PMID: 27052676 [PubMed - indexed for MEDLINE]

Association of a Novel Nonsense Mutation in KIAA1279 with Goldberg-Shprintzen Syndrome.

Iran J Child Neurol. 2017;11(1):70-74

Authors: Salehpour S, Hashemi-Gorji F, Soltani Z, Ghafouri-Fard S, Miryounesi M

Abstract
Goldberg-Shprintzen syndrome (OMIM 609460) (GOSHS) is an autosomal recessive multiple congenital anomaly syndrome distinguished by intellectual disability, microcephaly, and dysmorphic facial characteristics. Most affected individuals also have Hirschsprung disease and/or gyral abnormalities of the brain. This syndrome has been associated with KIAA1279 gene mutations at 10q22.1. Here we report a 16 yr old male patient referred to Center for Comprehensive Genetic Services, Tehran, Iran in 2015 with cardinal features of GOSHS in addition to refractory seizures. Whole exome sequencing in the patient revealed a novel nonsense (stop gain) homozygous mutation in KIAA1279 gene (KIAA1279: NM_015634:exon6:c.C976T:p.Q326X). Considering the wide range of phenotypic variations in GOSHS, relying on phenotypic characteristics for discrimination of GOSH from similar syndromes may lead to misdiagnosis. Consequently, molecular diagnostic tools would help in accurate diagnosis of such overlapping phenotypes.

PMID: 28277559 [PubMed - in process]

Identification of Disease-Causing Mutations by Functional Complementation of Patient-Derived Fibroblast Cell Lines.

Methods Mol Biol. 2017;1567:391-406

Authors: Kremer LS, Prokisch H

Abstract
Diagnosis of mitochondrial disorders is still hampered by their phenotypic and genotypic heterogeneity. In many cases, exome sequencing, the state-of-the-art method for genetically diagnosing mitochondrial disease patients, does not allow direct identification of the disease-associated gene but rather results in a list of variants in candidate genes. Here, we present a method to validate the disease-causing variant based on functional complementation assays. First, cell lines expressing a wild-type cDNA of the candidate genes are generated by lentiviral infection of patient-derived fibroblasts. Next, oxidative phosphorylation is measured by the Seahorse XF analyzer to assess rescue efficiency.

PMID: 28276032 [PubMed - in process]

Dihydropyrimidine Dehydrogenase Deficiency: Metabolic Disease or Biochemical Phenotype?

JIMD Rep. 2017 Mar 09;:

Authors: Fleger M, Willomitzer J, Meinsma R, Alders M, Meijer J, Hennekam RC, Huemer M, van Kuilenburg AB

Abstract
Dihydropyrimidine dehydrogenase (DPD) deficiency is an autosomal recessive disorder of pyrimidine metabolism that impairs the first step of uracil und thymine degradation. The spectrum of clinical presentations in subjects with the full biochemical phenotype of DPD deficiency ranges from asymptomatic individuals to severely affected patients suffering from seizures, microcephaly, muscular hypotonia, developmental delay and eye abnormalities.We report on a boy with intellectual disability, significant impairment of speech development, highly active epileptiform discharges on EEG, microcephaly and impaired gross-motor development. This clinical presentation triggered metabolic workup that demonstrated the biochemical phenotype of DPD deficiency, which was confirmed by enzymatic and molecular genetic studies. The patient proved to be homozygous for a novel c.2059-22T>G mutation which resulted in an in-frame insertion of 21 base pairs (c.2059-21_c.2059-1) of intron 16 of DPYD. Family investigation showed that the asymptomatic father was also homozygous for the same mutation and enzymatic and biochemical findings were similar to his severely affected son. When the child deteriorated clinically, exome sequencing was initiated under the hypothesis that DPD deficiency did not explain the phenotype completely. A deletion of the maternal allele on chromosome 15q11.2-13-1 was identified allowing the diagnosis of Angelman syndrome (AS). This diagnosis explains the patient's clinical presentation sufficiently; the influence of DPD deficiency on the phenotype, however, remains uncertain.

PMID: 28275972 [PubMed - as supplied by publisher]

Whole exome sequencing coupled with unbiased functional analysis reveals new Hirschsprung disease genes.

Genome Biol. 2017 Mar 08;18(1):48

Authors: Gui H, Schriemer D, Cheng WW, Chauhan RK, Antiňolo G, Berrios C, Bleda M, Brooks AS, Brouwer RW, Burns AJ, Cherny SS, Dopazo J, Eggen BJ, Griseri P, Jalloh B, Le TL, Lui VC, Luzón-Toro B, Matera I, Ngan ES, Pelet A, Ruiz-Ferrer M, Sham PC, Shepherd IT, So MT, Sribudiani Y, Tang CS, van den Hout MC, van der Linde HC, van Ham TJ, van IJcken WF, Verheij JB, Amiel J, Borrego S, Ceccherini I, Chakravarti A, Lyonnet S, Tam PK, Garcia-Barceló MM, Hofstra RM

Abstract
BACKGROUND: Hirschsprung disease (HSCR), which is congenital obstruction of the bowel, results from a failure of enteric nervous system (ENS) progenitors to migrate, proliferate, differentiate, or survive within the distal intestine. Previous studies that have searched for genes underlying HSCR have focused on ENS-related pathways and genes not fitting the current knowledge have thus often been ignored. We identify and validate novel HSCR genes using whole exome sequencing (WES), burden tests, in silico prediction, unbiased in vivo analyses of the mutated genes in zebrafish, and expression analyses in zebrafish, mouse, and human.
RESULTS: We performed de novo mutation (DNM) screening on 24 HSCR trios. We identify 28 DNMs in 21 different genes. Eight of the DNMs we identified occur in RET, the main HSCR gene, and the remaining 20 DNMs reside in genes not reported in the ENS. Knockdown of all 12 genes with missense or loss-of-function DNMs showed that the orthologs of four genes (DENND3, NCLN, NUP98, and TBATA) are indispensable for ENS development in zebrafish, and these results were confirmed by CRISPR knockout. These genes are also expressed in human and mouse gut and/or ENS progenitors. Importantly, the encoded proteins are linked to neuronal processes shared by the central nervous system and the ENS.
CONCLUSIONS: Our data open new fields of investigation into HSCR pathology and provide novel insights into the development of the ENS. Moreover, the study demonstrates that functional analyses of genes carrying DNMs are warranted to delineate the full genetic architecture of rare complex diseases.

PMID: 28274275 [PubMed - in process]

tRNA N6-adenosine threonylcarbamoyltransferase defect due to KAE1/TCS3 (OSGEP) mutation manifest by neurodegeneration and renal tubulopathy.

Eur J Hum Genet. 2017 Mar 08;:

Authors: Edvardson S, Prunetti L, Arraf A, Haas D, Bacusmo JM, Hu JF, Ta-Shma A, Dedon PC, de Crécy-Lagard V, Elpeleg O

Abstract
Post-transcriptional tRNA modifications are numerous and require a large set of highly conserved enzymes in humans and other organisms. In yeast, the loss of many modifications is tolerated under unstressed conditions; one exception is the N(6)-threonyl-carbamoyl-adenosine (t(6)A) modification, loss of which causes a severe growth phenotype. Here we aimed at a molecular diagnosis in a brother and sister from a consanguineous family who presented with global developmental delay, failure to thrive and a renal defect manifesting in proteinuria and hypomagnesemia. Using exome sequencing, the patients were found to be homozygous for the c.974G>A (p.(Arg325Gln)) variant of the KAE1 gene. KAE1 is a constituent of the KEOPS complex, a five-subunit complex that catalyzes the second biosynthetic step of t(6)A in the cytosol. The yeast KAE1 allele carrying the equivalent mutation did not rescue the t(6)A deficiency of the kae1Δ yeast strain as efficiently as the WT allele; furthermore, t(6)A levels quantified by LC-MS/MS were lower in the kae1Δ strain which was complemented by the mutation than in the kae1Δ strain, which was complemented by the WT allele. We conclude that homozygosity for c.974G>A (p.(Arg325Gln)) in KAE1 likely exerts its pathogenic effect by perturbing t(6)A synthesis, thereby interfering with global protein production. This is the first report of t(6)A biosynthesis defect in human. KAE1 joins the growing list of cytoplasmic tRNA modification enzymes, all associated with severe neurological disorders.European Journal of Human Genetics advance online publication, 8 March 2017; doi:10.1038/ejhg.2017.30.

PMID: 28272532 [PubMed - as supplied by publisher]

Association of Rare and Common Variation in the Lipoprotein Lipase Gene With Coronary Artery Disease.

JAMA. 2017 03 07;317(9):937-946

Authors: Khera AV, Won HH, Peloso GM, O'Dushlaine C, Liu D, Stitziel NO, Natarajan P, Nomura A, Emdin CA, Gupta N, Borecki IB, Asselta R, Duga S, Merlini PA, Correa A, Kessler T, Wilson JG, Bown MJ, Hall AS, Braund PS, Carey DJ, Murray MF, Kirchner HL, Leader JB, Lavage DR, Manus JN, Hartzel DN, Samani NJ, Schunkert H, Marrugat J, Elosua R, McPherson R, Farrall M, Watkins H, Lander ES, Rader DJ, Danesh J, Ardissino D, Gabriel S, Willer C, Abecasis GR, Saleheen D, Dewey FE, Kathiresan S, Myocardial Infarction Genetics Consortium, DiscovEHR Study Group, CARDIoGRAM Exome Consortium, and Global Lipids Genetics Consortium

Abstract
Importance: The activity of lipoprotein lipase (LPL) is the rate-determining step in clearing triglyceride-rich lipoproteins from the circulation. Mutations that damage the LPL gene (LPL) lead to lifelong deficiency in enzymatic activity and can provide insight into the relationship of LPL to human disease.
Objective: To determine whether rare and/or common variants in LPL are associated with early-onset coronary artery disease (CAD).
Design, Setting, and Participants: In a cross-sectional study, LPL was sequenced in 10 CAD case-control cohorts of the multinational Myocardial Infarction Genetics Consortium and a nested CAD case-control cohort of the Geisinger Health System DiscovEHR cohort between 2010 and 2015. Common variants were genotyped in up to 305 699 individuals of the Global Lipids Genetics Consortium and up to 120 600 individuals of the CARDIoGRAM Exome Consortium between 2012 and 2014. Study-specific estimates were pooled via meta-analysis.
Exposures: Rare damaging mutations in LPL included loss-of-function variants and missense variants annotated as pathogenic in a human genetics database or predicted to be damaging by computer prediction algorithms trained to identify mutations that impair protein function. Common variants in the LPL gene region included those independently associated with circulating triglyceride levels.
Main Outcomes and Measures: Circulating lipid levels and CAD.
Results: Among 46 891 individuals with LPL gene sequencing data available, the mean (SD) age was 50 (12.6) years and 51% were female. A total of 188 participants (0.40%; 95% CI, 0.35%-0.46%) carried a damaging mutation in LPL, including 105 of 32 646 control participants (0.32%) and 83 of 14 245 participants with early-onset CAD (0.58%). Compared with 46 703 noncarriers, the 188 heterozygous carriers of an LPL damaging mutation displayed higher plasma triglyceride levels (19.6 mg/dL; 95% CI, 4.6-34.6 mg/dL) and higher odds of CAD (odds ratio = 1.84; 95% CI, 1.35-2.51; P < .001). An analysis of 6 common LPL variants resulted in an odds ratio for CAD of 1.51 (95% CI, 1.39-1.64; P = 1.1 × 10-22) per 1-SD increase in triglycerides.
Conclusions and Relevance: The presence of rare damaging mutations in LPL was significantly associated with higher triglyceride levels and presence of coronary artery disease. However, further research is needed to assess whether there are causal mechanisms by which heterozygous lipoprotein lipase deficiency could lead to coronary artery disease.

PMID: 28267856 [PubMed - in process]

A truncating mutation in CEP55 is the likely cause of MARCH, a novel syndrome affecting neuronal mitosis.

J Med Genet. 2017 Mar 06;:

Authors: Frosk P, Arts HH, Philippe J, Gunn CS, Brown EL, Chodirker B, Simard L, Majewski J, Fahiminiya S, Russell C, Liu YP, FORGE Canada Consortium, Canadian Rare Diseases: Models & Mechanisms Network,, Hegele R, Katsanis N, Goerz C, Del Bigio MR, Davis EE

Abstract
BACKGROUND: Hydranencephaly is a congenital anomaly leading to replacement of the cerebral hemispheres with a fluid-filled cyst. The goals of this work are to describe a novel autosomal-recessive syndrome that includes hydranencephaly (multinucleated neurons, anhydramnios, renal dysplasia, cerebellar hypoplasia and hydranencephaly (MARCH)); to identify its genetic cause(s) and to provide functional insight into pathomechanism.
METHODS: We used homozygosity mapping and exome sequencing to identify recessive mutations in a single family with three affected fetuses. Immunohistochemistry, RT-PCR and imaging in cell lines, and zebrafish models, were used to explore the function of the gene and the effect of the mutation.
RESULTS: We identified a homozygous nonsense mutation in CEP55 segregating with MARCH. Testing the effect of this allele on patient-derived cells indicated both a reduction of the overall CEP55 message and the production of a message that likely gives rise to a truncated protein. Suppression or ablation of cep55l in zebrafish embryos recapitulated key features of MARCH, most notably renal dysplasia, cerebellar hypoplasia and craniofacial abnormalities. These phenotypes could be rescued by full-length but not truncated human CEP55 message. Finally, we expressed the truncated form of CEP55 in human cells, where we observed a failure of truncated protein to localise to the midbody, leading to abscission failure and multinucleated daughter cells.
CONCLUSIONS: CEP55 loss of function mutations likely underlie MARCH, a novel multiple congenital anomaly syndrome. This association expands the involvement of centrosomal proteins in human genetic disorders by highlighting a role in midbody function.

PMID: 28264986 [PubMed - as supplied by publisher]