Between-region genetic divergence reflects the mode and tempo of tumor evolution.

Nat Genet. 2017 Jul;49(7):1015-1024

Authors: Sun R, Hu Z, Sottoriva A, Graham TA, Harpak A, Ma Z, Fischer JM, Shibata D, Curtis C

Abstract
Given the implications of tumor dynamics for precision medicine, there is a need to systematically characterize the mode of evolution across diverse solid tumor types. In particular, methods to infer the role of natural selection within established human tumors are lacking. By simulating spatial tumor growth under different evolutionary modes and examining patterns of between-region subclonal genetic divergence from multiregion sequencing (MRS) data, we demonstrate that it is feasible to distinguish tumors driven by strong positive subclonal selection from those evolving neutrally or under weak selection, as the latter fail to dramatically alter subclonal composition. We developed a classifier based on measures of between-region subclonal genetic divergence and projected patient data into model space, finding different modes of evolution both within and between solid tumor types. Our findings have broad implications for how human tumors progress, how they accumulate intratumoral heterogeneity, and ultimately how they may be more effectively treated.

PMID: 28581503 [PubMed - indexed for MEDLINE]

Biallelic TRIP13 mutations predispose to Wilms tumor and chromosome missegregation.

Nat Genet. 2017 Jul;49(7):1148-1151

Authors: Yost S, de Wolf B, Hanks S, Zachariou A, Marcozzi C, Clarke M, de Voer R, Etemad B, Uijttewaal E, Ramsay E, Wylie H, Elliott A, Picton S, Smith A, Smithson S, Seal S, Ruark E, Houge G, Pines J, Kops GJPL, Rahman N

Abstract
Through exome sequencing, we identified six individuals with biallelic loss-of-function mutations in TRIP13. All six developed Wilms tumor. Constitutional mosaic aneuploidies, microcephaly, developmental delay and seizures, which are features of mosaic variegated aneuploidy (MVA) syndrome, were more variably present. Through functional studies, we show that TRIP13-mutant patient cells have no detectable TRIP13 and have substantial impairment of the spindle assembly checkpoint (SAC), leading to a high rate of chromosome missegregation. Accurate segregation, as well as SAC proficiency, is rescued by restoring TRIP13 function. Individuals with biallelic TRIP13 or BUB1B mutations have a high risk of embryonal tumors, and here we show that their cells display severe SAC impairment. MVA due to biallelic CEP57 mutations, or of unknown cause, is not associated with embryonal tumors and cells from these individuals show minimal SAC deficiency. These data provide insights into the complex relationships between aneuploidy and carcinogenesis.

PMID: 28553959 [PubMed - indexed for MEDLINE]

The complex genetics of hypoplastic left heart syndrome.

Nat Genet. 2017 Jul;49(7):1152-1159

Authors: Liu X, Yagi H, Saeed S, Bais AS, Gabriel GC, Chen Z, Peterson KA, Li Y, Schwartz MC, Reynolds WT, Saydmohammed M, Gibbs B, Wu Y, Devine W, Chatterjee B, Klena NT, Kostka D, de Mesy Bentley KL, Ganapathiraju MK, Dexheimer P, Leatherbury L, Khalifa O, Bhagat A, Zahid M, Pu W, Watkins S, Grossfeld P, Murray SA, Porter GA, Tsang M, Martin LJ, Benson DW, Aronow BJ, Lo CW

Abstract
Congenital heart disease (CHD) affects up to 1% of live births. Although a genetic etiology is indicated by an increased recurrence risk, sporadic occurrence suggests that CHD genetics is complex. Here, we show that hypoplastic left heart syndrome (HLHS), a severe CHD, is multigenic and genetically heterogeneous. Using mouse forward genetics, we report what is, to our knowledge, the first isolation of HLHS mutant mice and identification of genes causing HLHS. Mutations from seven HLHS mouse lines showed multigenic enrichment in ten human chromosome regions linked to HLHS. Mutations in Sap130 and Pcdha9, genes not previously associated with CHD, were validated by CRISPR-Cas9 genome editing in mice as being digenic causes of HLHS. We also identified one subject with HLHS with SAP130 and PCDHA13 mutations. Mouse and zebrafish modeling showed that Sap130 mediates left ventricular hypoplasia, whereas Pcdha9 increases penetrance of aortic valve abnormalities, both signature HLHS defects. These findings show that HLHS can arise genetically in a combinatorial fashion, thus providing a new paradigm for the complex genetics of CHD.

PMID: 28530678 [PubMed - indexed for MEDLINE]

Digenic Inheritance of PROKR2 and WDR11 Mutations in Pituitary Stalk Interruption Syndrome.

J Clin Endocrinol Metab. 2017 Jul 01;102(7):2501-2507

Authors: McCormack SE, Li D, Kim YJ, Lee JY, Kim SH, Rapaport R, Levine MA

Abstract
Context: Pituitary stalk interruption syndrome (PSIS, ORPHA95496) is a congenital defect of the pituitary gland characterized by the triad of a very thin/interrupted pituitary stalk, an ectopic (or absent) posterior pituitary gland, and hypoplasia or aplasia of the anterior pituitary gland. Complex genetic patterns of inheritance of this disorder are increasingly recognized.
Objective: The objective of this study was to identify a genetic cause of PSIS in an affected child.
Methods: Whole exome sequencing (WES) was performed by using standard techniques, with prioritized genetic variants confirmed via Sanger sequencing. To investigate the effects of one candidate variant on mutant WDR11 function, Western blotting and coimmunofluorescence were used to assess binding capacity, and leptomycin B exposure along with immunofluorescence was used to assess nuclear localization.
Results: We describe a child who presented in infancy with combined pituitary hormone deficiencies and whose brain imaging demonstrated a small anterior pituitary, ectopic posterior pituitary, and a thin, interrupted stalk. WES demonstrated heterozygous missense mutations in two genes required for pituitary development, a known loss-of-function mutation in PROKR2 (c.253C>T;p.R85C) inherited from an unaffected mother, and a WDR11 (c.1306A>G;p.I436V) mutation inherited from an unaffected father. Mutant WDR11 loses its capacity to bind to its functional partner, EMX1, and to localize to the nucleus.
Conclusions: WES in a child with PSIS and his unaffected family implicates a digenic mechanism of inheritance. In cases of hypopituitarism in which there is incomplete segregation of a monogenic genotype with the phenotype, the possibility that a second genetic locus is involved should be considered.

PMID: 28453858 [PubMed - indexed for MEDLINE]

Mutations in the Human ROBO1 Gene in Pituitary Stalk Interruption Syndrome.

J Clin Endocrinol Metab. 2017 Jul 01;102(7):2401-2406

Authors: Bashamboo A, Bignon-Topalovic J, Moussi N, McElreavey K, Brauner R

Abstract
Context: Pituitary stalk interruption syndrome (PSIS) is characterized by a thin or absent pituitary stalk usually in association with an ectopic posterior pituitary and hypoplasia/aplasia of the anterior pituitary. Associated phenotypes include varied ocular anomalies, hypoglycemia, micropenis/cryptorchidism, growth failure, or combined pituitary hormone deficiencies. Although genetic causes have been identified, they explain only around 5% of PSIS cases.
Objective: To identify genetic causes of PSIS by exome sequencing.
Design: Exon enrichment was performed using the Agilent SureSelect Human All Exon V4. Paired-end sequencing was performed on the Illumina HiSeq2000 platform with an average sequencing coverage of ×50.
Patients: Patients with unexplained PSIS were included in the study.
Results: In five cases of unexplained PSIS including two familial cases, we identified a novel heterozygous frameshift and nonsense and missense mutations in the ROBO1 gene (p.Ala977Glnfs*40, two affected sibs; p.Tyr1114Ter, sporadic case, and p.Cys240Ser, affected child and paternal aunt) that controls embryonic axon guidance, and branching in the nervous system. Interestingly, four of the five cases of PSIS also presented with ocular anomalies, including hypermetropia with strabismus as well as ptosis.
Conclusions: These data suggest that mutations in ROBO1 contribute to PSIS and associated ocular anomalies.

PMID: 28402530 [PubMed - indexed for MEDLINE]

Somatic HLA Mutations Expose the Role of Class I-Mediated Autoimmunity in Aplastic Anemia and its Clonal Complications.

Blood Adv. 2017 Oct 10;1(22):1900-1910

Authors: Babushok DV, Duke JL, Xie HM, Stanley N, Atienza J, Perdigones N, Nicholas P, Ferriola D, Li Y, Huang H, Ye W, Morrissette JJD, Kearns J, Porter DL, Podsakoff GM, Eisenlohr LC, Biegel JA, Chou ST, Monos DS, Bessler M, Olson TS

Abstract
Acquired aplastic anemia (aAA) is an acquired deficiency of early hematopoietic cells, characterized by inadequate blood production, and a predisposition to myelodysplastic syndrome (MDS) and leukemia. Although its exact pathogenesis is unknown, aAA is thought to be driven by Human Leukocyte Antigen (HLA)-restricted T cell immunity, with earlier studies favoring HLA class II-mediated pathways. Using whole exome sequencing (WES), we recently identified two aAA patients with somatic mutations in HLA class I genes. We hypothesized that HLA class I mutations are pathognomonic for autoimmunity in aAA, but were previously underappreciated because the Major Histocompatibility Complex (MHC) region is notoriously difficult to analyze by WES. Using a combination of targeted deep sequencing of HLA class I genes and single nucleotide polymorphism array (SNP-A) genotyping we screened 66 aAA patients for somatic HLA class I loss. We found somatic HLA loss in eleven patients (17%), with thirteen loss-of-function mutations in HLA-A*33:03, HLA-A*68:01, HLA-B*14:02 and HLA-B*40:02 alleles. Three patients had more than one mutation targeting the same HLA allele. Interestingly, HLA-B*14:02 and HLA-B*40:02 were significantly overrepresented in aAA patients, compared to ethnicity-matched controls. Patients who inherited the targeted HLA alleles, regardless of HLA mutation status, had a more severe disease course with more frequent clonal complications as assessed by WES, SNP-A, and metaphase cytogenetics, and more frequent secondary MDS. The finding of recurrent HLA class I mutations provides compelling evidence for a predominant HLA class I-driven autoimmunity in aAA, and establishes a novel link between aAA patients' immunogenetics and clonal evolution.

PMID: 28971166 [PubMed]

Defective mitochondrial rRNA methyltransferase MRM2 causes MELAS-like clinical syndrome.

Hum Mol Genet. 2017 Aug 25;:

Authors: Garone C, D'Souza AR, Dallabona C, Lodi T, Rebelo-Guiomar P, Rorbach J, Donati MA, Procopio E, Montomoli M, Guerrini R, Zeviani M, Calvo SE, Mootha VK, DiMauro S, Ferrero I, Minczuk M

Abstract
Defects in nuclear-encoded proteins of the mitochondrial translation machinery cause early-onset and tissue-specific deficiency of one or more OXPHOS complexes. Here, we report a 7-year-old Italian boy with childhood-onset rapidly progressive encephalomyopathy and stroke-like episodes. Multiple OXPHOS defects and decreased mtDNA copy number (40%) were detected in muscle homogenate. Clinical features combined with low level of plasma citrulline were highly suggestive of mitochondrial encephalopathy, lactic acidosis and stroke-like episodes (MELAS) syndrome, however, the common m.3243A>G mutation was excluded. Targeted exome sequencing of genes encoding the mitochondrial proteome identified a damaging mutation, c.567G>A, affecting a highly conserved amino acid residue (p.Gly189Arg) of the MRM2 protein. MRM2 has never before been linked to a human disease and encodes an enzyme responsible for 2'-O-methyl modification at position U1369 in the human mitochondrial 16S rRNA. We generated a knockout yeast model for the orthologous gene that showed a defect in respiration and the reduction of the 2'-O-methyl modification at the equivalent position (U2791) in the yeast mitochondrial 21S rRNA. Complementation with the mrm2 allele carrying the equivalent yeast mutation failed to rescue the respiratory phenotype, which was instead completely rescued by expressing the wild-type allele. Our findings establish that defective MRM2 causes a MELAS-like phenotype, and suggests the genetic screening of the MRM2 gene in patients with a m.3243A>G negative MELAS-like presentation.

PMID: 28973171 [PubMed - as supplied by publisher]

A constitutive BCL2 down-regulation aggravates the phenotype of PKD1-mutant induced polycystic kidney disease.

Hum Mol Genet. 2017 Sep 11;:

Authors: Duplomb L, Droin N, Bouchot O, Thauvin CR, Bruel AL, Thevenon J, Callier P, Meurice G, Pata-Merci N, Loffroy R, Vandroux D, Da Costa R, Carmignac V, Solary E, Faivre L

Abstract
The main identified function of BCL2 protein is to prevent cell death by apoptosis. Mice knock-out for Bcl2 demonstrate growth retardation, severe polycystic kidney disease (PKD), gray hair and lymphopenia, and die prematurely after birth. Here, we report a 40-year-old male referred to for abdominal and thoracic aortic dissection with associated aortic root aneurysm, PKD, lymphocytopenia with a history of T cell lymphoblastic lymphoma, white hair since the age of 20, and learning difficulties. PKD, which was also detected in the father and sister, was related to an inherited PKD1 mutation. The combination of PKD with gray hair and lymphocytopenia was also reminiscent of Bcl2-/- mouse phenotype. BCL2 gene transcript and protein level were observed to be dramatically decreased in patient peripheral blood T-cells and in his aorta vascular wall cells, which was not detected in parents and sister T-cells, suggesting an autosomal recessive inheritance. Accordingly, spontaneous apoptosis of patient T-cells was increased and could be rescued through stimulation with an anti-CD3 antibody. Direct sequencing of BCL2 gene exons, promoter and 3'UTR region as well as BCL2 mRNA sequencing failed in identifying any pathogenic variant. Array-CGH was also normal and whole exome sequencing of the patient, parents and sister DNA did not detect any significant variant in genes encoding Bcl2-interacting proteins. miRNA array identified an up-regulation of miR-181a, which is a known regulator of BCL2 expression. Altogether, miR-181a-mediated decrease in BCL2 gene expression could be a modifying factor that aggravates the phenotype of a PKD1 constitutive variant.

PMID: 28973148 [PubMed - as supplied by publisher]

Multiregional sequencing reveals genomic alterations and clonal dynamics in primary malignant melanoma of the esophagus.

Cancer Res. 2017 Sep 29;:

Authors: Li J, Yan S, Liu Z, Zhou Y, Pan Y, Yuan W, Liu M, Tan Q, Tian G, Dong B, Cai H, Wu N, Ke Y

Abstract
Primary malignant melanoma of the esophagus (PMME) is a rare and aggressive disease with high tendency of metastasis. To characterize the genetic basis and intra-tumor heterogeneity of PMME, we performed multiregion exome sequencing and whole genome SNP array genotyping of 12 samples obtained from a PMME patient. High intra-tumor heterogeneity was observed in both somatic mutation and copy number alteration levels. Nine geographically separate samples including two normal samples were clonally related and followed a branched evolution model. Most putative oncogenic drivers such as BRAF and KRAS mutations as well as CDKN2A biallelic inactivation were observed in trunk clones, whereas clinically actionable mutations such as PIK3CA and JAK1 mutations were detected in branch clones. Ancestor tumor clones evolved into three subclonal clades: clade1 fostered metastatic subclones that carried metastatic features of PIK3CA and ARHGAP26 point mutations as well as chr13 arm-level deletion, clade2 owned branch-specific JAK1 mutations and PTEN deletion, and clade3 was found in two vertical distribution samples below the primary tumor area, highlighting the fact that it is possible for PMME to disseminate by the submucosal longitudinal lymphatic route at an early stage of metastasis. These findings facilitate interpretation of the genetic essence of this rare melanoma subtype as well as the pattern of cancer evolution, thus reinforcing the therapeutic challenges associated with PMME.

PMID: 28972077 [PubMed - as supplied by publisher]

Autosomal dominant transmission of complicated hereditary spastic paraplegia due to a dominant negative mutation of KIF1A, SPG30 gene.

Sci Rep. 2017 Oct 02;7(1):12527

Authors: Cheon CK, Lim SH, Kim YM, Kim D, Lee NY, Yoon TS, Kim NS, Kim E, Lee JR

Abstract
KIF1A is a brain-specific anterograde motor protein that transports cargoes towards the plus-ends of microtubules. Many variants of the KIF1A gene have been associated with neurodegenerative diseases and developmental delay. Homozygous mutations of KIF1A have been identified in a recessive subtype of hereditary spastic paraplegia (HSP), SPG30. In addition, KIF1A mutations have been found in pure HSP with autosomal dominant inheritance. Here we report the first case of familial complicated HSP with a KIF1A mutation transmitted in autosomal dominant inheritance. A heterozygous p.T258M mutation in KIF1A was found in a Korean family through targeted exome sequencing. They displayed phenotypes of mild intellectual disability with language delay, epilepsy, optic nerve atrophy, thinning of corpus callosum, periventricular white matter lesion, and microcephaly. A structural modeling revealed that the p.T258M mutation disrupted the binding of KIF1A motor domain to microtubules and its movement along microtubules. Assays of peripheral accumulation and proximal distribution of KIF1A motor indicated that the KIF1A motor domain with p.T258M mutation has reduced motor activity and exerts a dominant negative effect on wild-type KIF1A. These results suggest that the p.T258M mutation suppresses KIF1A motor activity and induces complicated HSP accompanying intellectual disability transmitted in autosomal dominant inheritance.

PMID: 28970574 [PubMed - in process]

Tumor PD-L1 expression is associated with improved survival and lower recurrence risk in young women with oral cavity squamous cell carcinoma.

Int J Oral Maxillofac Surg. 2017 Sep 29;:

Authors: Hanna GJ, Woo SB, Li YY, Barletta JA, Hammerman PS, Lorch JH

Abstract
Young patients with oral cavity squamous cell carcinoma (OCSCC) are often recognized as a distinct epidemiological cohort. In this study, genomic and immune-based metrics were correlated with long-term outcomes for a young patient population treated at a single institution. A fully clinically annotated, retrospective cohort of 81 patients aged ≤45 years with OCSCC is described, and the impact of clinicopathological features on long-term survival outcomes is reported. Genomic and immune parameters were integrated utilizing a whole-exome sequencing and immunohistochemical approach among females in the cohort. It was found that young OCSCC patients had favorable outcomes (10-year disease-free survival 79.1%, overall survival 80.0%) regardless of sex, particularly if they presented with oral tongue primaries and early stage disease. While mutational analysis appeared similar to that of older patients with OCSCC who lack a smoking history, a comparatively high degree of PD-L1 expression and PD-1/L1 concordance (P=0.001) was found among young female OCSCC patients. Subjects with greater membranous PD-L1 positivity and the presence of tumor-infiltrating lymphocytes had a decreased risk of recurrence (P=0.01 and P=0.01, respectively) and improved survival (P=0.04 and P=0.03, respectively). These findings warrant further validation and support the investigation of immunotherapeutic approaches targeting PD-1/L1 interactions in young OCSCC patients.

PMID: 28969885 [PubMed - as supplied by publisher]

Mutations in DNM1L, as in OPA1, result indominant optic atrophy despite opposite effectson mitochondrial fusion and fission.

Brain. 2017 Oct 01;140(10):2586-2596

Authors: Gerber S, Charif M, Chevrollier A, Chaumette T, Angebault C, Kane MS, Paris A, Alban J, Quiles M, Delettre C, Bonneau D, Procaccio V, Amati-Bonneau P, Reynier P, Leruez S, Calmon R, Boddaert N, Funalot B, Rio M, Bouccara D, Meunier I, Sesaki H, Kaplan J, Hamel CP, Rozet JM, Lenaers G

Abstract
Dominant optic atrophy is a blinding disease due to the degeneration of the retinal ganglion cells, the axons of which form the optic nerves. In most cases, the disease is caused by mutations in OPA1, a gene encoding a mitochondrial large GTPase involved in cristae structure and mitochondrial network fusion. Using exome sequencing, we identified dominant mutations in DNM1L on chromosome 12p11.21 in three large families with isolated optic atrophy, including the two families that defined the OPA5 locus on chromosome 19q12.1-13.1, the existence of which is denied by the present study. Analyses of patient fibroblasts revealed physiological abundance and homo-polymerization of DNM1L, forming aggregates in the cytoplasm and on highly tubulated mitochondrial network, whereas neither structural difference of the peroxisome network, nor alteration of the respiratory machinery was noticed. Fluorescence microscopy of wild-type mouse retina disclosed a strong DNM1L expression in the ganglion cell layer and axons, and comparison between 3-month-old wild-type and Dnm1l+/- mice revealed increased mitochondrial length in retinal ganglion cell soma and axon, but no degeneration. Thus, our results disclose that in addition to OPA1, OPA3, MFN2, AFG3L2 and SPG7, dominant mutations in DNM1L jeopardize the integrity of the optic nerve, suggesting that alterations of the opposing forces governing mitochondrial fusion and fission, similarly affect retinal ganglion cell survival.

PMID: 28969390 [PubMed - in process]

WDR81 mutations cause extreme microcephaly and impair mitotic progression in human fibroblasts and Drosophila neural stem cells.

Brain. 2017 Oct 01;140(10):2597-2609

Authors: Cavallin M, Rujano MA, Bednarek N, Medina-Cano D, Bernabe Gelot A, Drunat S, Maillard C, Garfa-Traore M, Bole C, Nitschké P, Beneteau C, Besnard T, Cogné B, Eveillard M, Kuster A, Poirier K, Verloes A, Martinovic J, Bidat L, Rio M, Lyonnet S, Reilly ML, Boddaert N, Jenneson-Liver M, Motte J, Doco-Fenzy M, Chelly J, Attie-Bitach T, Simons M, Cantagrel V, Passemard S, Baffet A, Thomas S, Bahi-Buisson N

Abstract
Microlissencephaly is a rare brain malformation characterized by congenital microcephaly and lissencephaly. Microlissencephaly is suspected to result from abnormalities in the proliferation or survival of neural progenitors. Despite the recent identification of six genes involved in microlissencephaly, the pathophysiological basis of this condition remains poorly understood. We performed trio-based whole exome sequencing in seven subjects from five non-consanguineous families who presented with either microcephaly or microlissencephaly. This led to the identification of compound heterozygous mutations in WDR81, a gene previously associated with cerebellar ataxia, intellectual disability and quadrupedal locomotion. Patient phenotypes ranged from severe microcephaly with extremely reduced gyration with pontocerebellar hypoplasia to moderate microcephaly with cerebellar atrophy. In patient fibroblast cells, WDR81 mutations were associated with increased mitotic index and delayed prometaphase/metaphase transition. Similarly, in vivo, we showed that knockdown of the WDR81 orthologue in Drosophila led to increased mitotic index of neural stem cells with delayed mitotic progression. In summary, we highlight the broad phenotypic spectrum of WDR81-related brain malformations, which include microcephaly with moderate to extremely reduced gyration and cerebellar anomalies. Our results suggest that WDR81 might have a role in mitosis that is conserved between Drosophila and humans.

PMID: 28969387 [PubMed - in process]

TUBB2B Mutation in an Adult Patient with Myoclonus-Dystonia.

Case Rep Neurol. 2017 May-Aug;9(2):216-221

Authors: Geiger JT, Schindler AB, Blauwendraat C, Singer HS, Scholz SW

Abstract
BACKGROUND: Tubulin mutations are a cause of neuronal migrational disorders referred to as tubulinopathies. Mutations in tubulin genes can have a severe impact on microtubule function and result in heterogeneous clinical presentations. Current understanding of the clinical spectrum of tubulinopathies is predominantly based on research in fetal tissue and early-childhood cases.
METHODS: Testing of candidate genes followed by whole-exome sequencing was performed in an adult woman with a neurodevelopmental, hyperkinetic movement disorder, to identify the underlying genetic cause. Bioinformatic modeling and a systematic review of literature was conducted to investigate genotype-phenotype correlations.
RESULTS: The patient was found to carry a heterozygous, de novo c.722G>A, p.R241H mutation in a conserved domain of TUBB2B, encoding the β-isoform of tubulin. In silico analysis indicated that this mutation was pathogenic. On neuroimaging, the patient had asymmetric pachygyria and dysmorphic basal ganglia. Her neurological examination demonstrated mild cognitive impairment, myoclonus-dystonia, and skeletal anomalies.
CONCLUSIONS: Here, we report the unique phenotype of an adult TUBB2B mutation carrier. This case illustrates a relatively mild phenotype compared to previously described fetal and early childhood cases. This highlights the importance of obtaining molecular genetic testing in individuals with a high probability of a genetic disease, including undiagnosed adult patients.

PMID: 28966590 [PubMed]

Integrated Molecular Meta-Analysis of 1,000 Pediatric High-Grade and Diffuse Intrinsic Pontine Glioma.

Cancer Cell. 2017 Sep 26;:

Authors: Mackay A, Burford A, Carvalho D, Izquierdo E, Fazal-Salom J, Taylor KR, Bjerke L, Clarke M, Vinci M, Nandhabalan M, Temelso S, Popov S, Molinari V, Raman P, Waanders AJ, Han HJ, Gupta S, Marshall L, Zacharoulis S, Vaidya S, Mandeville HC, Bridges LR, Martin AJ, Al-Sarraj S, Chandler C, Ng HK, Li X, Mu K, Trabelsi S, Brahim DH, Kisljakov AN, Konovalov DM, Moore AS, Carcaboso AM, Sunol M, de Torres C, Cruz O, Mora J, Shats LI, Stavale JN, Bidinotto LT, Reis RM, Entz-Werle N, Farrell M, Cryan J, Crimmins D, Caird J, Pears J, Monje M, Debily MA, Castel D, Grill J, Hawkins C, Nikbakht H, Jabado N, Baker SJ, Pfister SM, Jones DTW, Fouladi M, von Bueren AO, Baudis M, Resnick A, Jones C

Abstract
We collated data from 157 unpublished cases of pediatric high-grade glioma and diffuse intrinsic pontine glioma and 20 publicly available datasets in an integrated analysis of >1,000 cases. We identified co-segregating mutations in histone-mutant subgroups including loss of FBXW7 in H3.3G34R/V, TOP3A rearrangements in H3.3K27M, and BCOR mutations in H3.1K27M. Histone wild-type subgroups are refined by the presence of key oncogenic events or methylation profiles more closely resembling lower-grade tumors. Genomic aberrations increase with age, highlighting the infant population as biologically and clinically distinct. Uncommon pathway dysregulation is seen in small subsets of tumors, further defining the molecular diversity of the disease, opening up avenues for biological study and providing a basis for functionally defined future treatment stratification.

PMID: 28966033 [PubMed - as supplied by publisher]

The study of familial hypercholesterolemia in Italy: A narrative review.

Atheroscler Suppl. 2017 Oct;29:1-10

Authors: Bertolini S, Pisciotta L, Fasano T, Rabacchi C, Calandra S

Abstract
In this review we outline our experience in the clinical and molecular diagnosis of familial hypercholesterolemia (FH), built up over more than three decades. We started our work by selecting FH patients on the basis of stringent clinical criteria, including extensive family studies. In most patients we confirmed the clinical diagnosis by showing a reduced LDLR activity in skin fibroblasts. After the isolation of LDLR cDNA and the characterization of the corresponding gene by the Dallas group, we started a systematic molecular investigation of our patients first using Southern blotting, and, subsequently Sanger sequencing. Up to now we have been able to identify 260 mutations of LDLR gene in more than 1000 genotyped FH patients, including 68 homozygotes. During this survey we identified 13 mutation clusters located in different geographical districts, which gave us the chance to compare the phenotype of patients carrying the most common mutations. We also found that mutations in APOB and PCSK9 genes were a rare cause of FH in our cohort. Despite our efforts, we failed to identify mutations in candidate genes in ∼20% of cases of definite FH. An exome-wide study, conducted within the context of an international collaboration, excluded the presence of other major genes in our unexplained FH cases. Recently, we have adopted sequencing technology of the next generation (NGS) with the parallel sequencing of a panel of FH targeted genes as a way of obtaining a more comprehensive picture of the gene variants potentially involved in the disease.

PMID: 28965614 [PubMed - in process]

Differential analysis between somatic mutation and germline variation profiles reveals cancer-related genes.

Genome Med. 2017 Aug 25;9(1):79

Authors: Przytycki PF, Singh M

Abstract
A major aim of cancer genomics is to pinpoint which somatically mutated genes are involved in tumor initiation and progression. We introduce a new framework for uncovering cancer genes, differential mutation analysis, which compares the mutational profiles of genes across cancer genomes with their natural germline variation across healthy individuals. We present DiffMut, a fast and simple approach for differential mutational analysis, and demonstrate that it is more effective in discovering cancer genes than considerably more sophisticated approaches. We conclude that germline variation across healthy human genomes provides a powerful means for characterizing somatic mutation frequency and identifying cancer driver genes. DiffMut is available at https://github.com/Singh-Lab/Differential-Mutation-Analysis .

PMID: 28841835 [PubMed - indexed for MEDLINE]

Contribution of exome sequencing for genetic diagnostic in arrhythmogenic right ventricular cardiomyopathy/dysplasia.

PLoS One. 2017;12(8):e0181840

Authors: Fedida J, Fressart V, Charron P, Surget E, Hery T, Richard P, Donal E, Keren B, Duthoit G, Hidden-Lucet F, Villard E, Gandjbakhch E

Abstract
BACKGROUND: Arrhythmogenic Right Ventricular Cardiomyopathy/Dysplasia (ARVC/D) is an inherited cardiomyopathy mainly caused by heterozygous desmosomal gene mutations, the major gene being PKP2. The genetic cause remains unknown in ~50% of probands with routine desmosomal gene screening. The aim of this study was to assess the diagnostic accuracy of whole exome sequencing (WES) in ARVC/D with negative genetic testing.
METHODS: WES was performed in 22 patients, all without a mutation identified in desmosomal genes. Putative pathogenic variants were screened in 96 candidate genes associated with other cardiomyopathies/channelopathies. The sequencing coverage depth of PKP2, DSP, DSG2, DSC2, JUP and TMEM43 exons was compared to the mean coverage distribution to detect large insertions/deletions. All suspected deletions were verified by real-time qPCR, Multiplex-Ligation-dependent-Probe-Amplification (MLPA) and cGH-Array. MLPA was performed in 50 additional gene-negative probands.
RESULTS: Coverage-depth analysis from the 22 WES data identified two large heterozygous PKP2 deletions: one from exon 1 to 14 and one restricted to exon 4, confirmed by qPCR and MLPA. MLPA identified 2 additional PKP2 deletions (exon 1-7 and exon 1-14) in 50 additional probands confirming a significant frequency of large PKP2 deletions (5.7%) in gene-negative ARVC/D. Putative pathogenic heterozygous variants in EYA4, RBM20, PSEN1, and COX15 were identified in 4 unrelated probands.
CONCLUSION: A rather high frequency (5.7%) of large PKP2 deletions, undetectable by Sanger sequencing, was detected as the cause of ARVC/D. Coverage-depth analysis through next-generation sequencing appears accurate to detect large deletions at the same time than conventional putative mutations in desmosomal and cardiomyopathy-associated genes.

PMID: 28767663 [PubMed - indexed for MEDLINE]

Candidate Genes for Nonsyndromic Cleft Palate Detected by Exome Sequencing.

J Dent Res. 2017 Oct;96(11):1314-1321

Authors: Hoebel AK, Drichel D, van de Vorst M, Böhmer AC, Sivalingam S, Ishorst N, Klamt J, Gölz L, Alblas M, Maaser A, Keppler K, Zink AM, Dixon MJ, Dixon J, Hemprich A, Kruse T, Graf I, Dunsche A, Schmidt G, Daratsianos N, Nowak S, Aldhorae KA, Nöthen MM, Knapp M, Thiele H, Gilissen C, Reutter H, Hoischen A, Mangold E, Ludwig KU

Abstract
Nonsyndromic cleft palate only (nsCPO) is a facial malformation that has a livebirth prevalence of 1 in 2,500. Research suggests that the etiology of nsCPO is multifactorial, with a clear genetic component. To date, genome-wide association studies have identified only 1 conclusive common variant for nsCPO, that is, a missense variant in the gene grainyhead-like-3 ( GRHL3). Thus, the underlying genetic causes of nsCPO remain largely unknown. The present study aimed at identifying rare variants that might contribute to nsCPO risk, via whole-exome sequencing (WES), in multiply affected Central European nsCPO pedigrees. WES was performed in 2 affected first-degree relatives from each family. Variants shared between both individuals were analyzed for their potential deleterious nature and a low frequency in the general population. Genes carrying promising variants were annotated for 1) reported associations with facial development, 2) multiple occurrence of variants, and 3) expression in mouse embryonic palatal shelves. This strategy resulted in the identification of a set of 26 candidate genes that were resequenced in 132 independent nsCPO cases and 623 independent controls of 2 different ethnicities, using molecular inversion probes. No rare loss-of-function mutation was identified in either WES or resequencing step. However, we identified 2 or more missense variants predicted to be deleterious in each of 3 genes ( ACACB, PTPRS, MIB1) in individuals from independent families. In addition, the analyses identified a novel variant in GRHL3 in 1 patient and a variant in CREBBP in 2 siblings. Both genes underlie different syndromic forms of CPO. A plausible hypothesis is that the apparently nonsyndromic clefts in these 3 patients might represent hypomorphic forms of the respective syndromes. In summary, the present study identified rare variants that might contribute to nsCPO risk and suggests candidate genes for further investigation.

PMID: 28767323 [PubMed - indexed for MEDLINE]

ENPP1 Mutation Causes Recessive Cole Disease by Altering Melanogenesis.

J Invest Dermatol. 2017 Sep 27;:

Authors: Chourabi M, Liew MS, Lim S, H'mida-Ben Brahim D, Boussofara L, Dai L, Wong PM, Foo JN, Sriha B, Robinson KS, Denil S, Common JE, Mamaï O, Ben Khalifa Y, Bollen M, Liu J, Denguezli M, Bonnard C, Saad A, Reversade B

Abstract
Cole disease is a genodermatosis of pigmentation following a strict dominant mode of inheritance. In this study we investigated eight patients affected with an overlapping genodermatosis following recessive inheritance. The patients presented with hypo- and hyper-pigmented macules over the body, resembling dyschromatosis universalis hereditaria in addition to punctuate palmoplantar keratosis. By homozygosity mapping and whole-exome sequencing, a biallelic p.Cys120Arg mutation in Ectonucleotide pyrophosphatase/phosphodiesterase 1 (ENPP1) was identified in all patients. We found that this mutation, like those causing dominant Cole disease, impairs homo-dimerization of the ENPP1 enzyme which is mediated by its two somatomedin-B-like domains. Histological analysis revealed structural and molecular changes in affected skin which were likely to originate from defective melanocytes since keratinocytes do not express ENPP1. Consistently, RNA-seq analysis of patient-derived primary melanocytes revealed alterations in melanocyte development and in pigmentation signaling pathways. We therefore conclude that germline ENPP1 cysteine-specific mutations, primarily affecting the melanocyte lineage, cause a clinical spectrum of dyschromatosis, in which the p.Cys120Arg allele represents a recessive and more severe form of Cole disease.

PMID: 28964717 [PubMed - as supplied by publisher]