Molecular and Functional Characterization of Rare CACNA1C Variants in Sudden Unexplained Death in the Young.

Congenit Heart Dis. 2016 Dec;11(6):683-692

Authors: Sutphin BS, Boczek NJ, Barajas-Martínez H, Hu D, Ye D, Tester DJ, Antzelevitch C, Ackerman MJ

Abstract
INTRODUCTION: Perturbations in the CACNA1C-encoded L-type calcium channel α-subunit have been linked recently to heritable arrhythmia syndromes, including Timothy syndrome, Brugada syndrome, early repolarization syndrome, and long QT syndrome. These heritable arrhythmia syndromes may serve as a pathogenic basis for autopsy-negative sudden unexplained death in the young (SUDY). However, the contribution of CACNA1C mutations to SUDY is unknown.
OBJECTIVE: We set out to determine the spectrum, prevalence, and pathophysiology of rare CACNA1C variants in SUDY.
METHODS: Mutational analysis of CACNA1C was conducted in 82 SUDY cases using polymerase chain reaction, denaturing high-performance liquid chromatography, and direct sequencing. Identified variants were engineered using site-directed mutagenesis, and heterologously expressed in TSA-201 or HEK293 cells.
RESULTS: Two SUDY cases (2.4%) harbored functional variants in CACNA1C. The E850del and N2091S variants involve highly conserved residues and localize to the II-III linker and C-terminus, respectively. Although observed in publically available exome databases, both variants confer abnormal CaV 1.2 electrophysiological characteristics. Examination of the electrophysiological properties revealed the E850del mutation in CACNA1C led to a 95% loss-of-function in ICa , and the N2091S variant led to a 105% gain-of-function in ICa. Additionally, N2091S led to minor kinetic alterations including a -3.4 mV shift in V1/2 of activation.
CONCLUSION: This study provides molecular and functional evidence that rare CACNA1C genetic variants may contribute to the underlying pathogenic basis for some cases of SUDY in either a gain or loss-of-function mechanism.

PMID: 27218670 [PubMed - indexed for MEDLINE]

Next-generation sequencing of urine specimens: A novel platform for genomic analysis in patients with non-muscle-invasive urothelial carcinoma treated with bacille Calmette-Guérin.

Cancer. 2017 Mar 24;:

Authors: Scott SN, Ostrovnaya I, Lin CM, Bouvier N, Bochner BH, Iyer G, Solit D, Berger MF, Lin O

Abstract
BACKGROUND: Biopsies from patients with high-risk (HR) non-muscle-invasive urothelial carcinoma (NMIUC), especially flat urothelial carcinoma in situ, frequently contain scant diagnostic material or denuded mucosa only, and this precludes further extensive genomic analysis. This study evaluated the use of next-generation sequencing (NGS) analysis of urine cytology material from patients with HR NMIUC in an attempt to identify genetic alterations that might correlate with clinical features and responses to bacille Calmette-Guérin (BCG) treatment.
METHODS: Forty-one cytology slides from patients with HR NMIUC treated with intravesical BCG were selected for this study. Histological confirmation was available for all cases. The specimens were subjected to NGS analysis with a customized targeted exome capture assay composed of 341 genes.
RESULTS: In this cohort, genomic alterations were successfully identified in all cytology samples. Mutations were detected down to a 2% allele frequency and chromosomal rearrangements including copy number alterations and gene fusions were identified. The most frequently altered genes included telomerase reverse transcriptase (TERT), tumor protein 53 (TP53), Erb-B2 receptor tyrosine kinase 2 (ERBB2), and chromatin remodeling genes such as lysine demethylase 6A (KDM6A) and AT-rich interaction domain 1A (ARID1A). For patients with matched tumor tissue, cytology specimens revealed all mutations detected in tissue as well as additional mutations, and this suggested that urine might more effectively capture the full genetic heterogeneity of disease than an individual cystectomy. Alterations in multiple genes correlated with clinical and histopathological features, including responses to BCG treatment, flat architecture versus papillary architecture, and smoking history.
CONCLUSIONS: Urine specimens can replace tissue as a substrate for NGS analysis of HR NMIUC. Several genomic alterations identified in urine specimens might be associated with histological features and clinical characteristics. Cancer Cytopathol 2017. © 2017 American Cancer Society.

PMID: 28339163 [PubMed - as supplied by publisher]

Exome sequencing in Thai patients with familial obesity.

Genet Mol Res. 2016 Jul 14;15(2):

Authors: Kaewsutthi S, Santiprabhob J, Phonrat B, Tungtrongchitr A, Lertrit P, Tungtrongchitr R

Abstract
Obesity is a major worldwide health issue, with increasing prevalence in adults and children from developed and developing countries. Obesity causes several chronic diseases, including cardiovascular and respiratory diseases, osteoarthritis, hypertension, stroke, type II diabetes, obstructive sleep apnea, and several types of cancer. Previous genome-wide association studies have identified several genes associated with obesity, including LEP, LEPR, POMC, PCSK1, FTO, MC3R, MC4R, GNPDA2, TMEM18, QPCTL/GIPR, BDNF, ETV5, MAP2K5/SKOR1, SEC16B, SIM1, and TNKS/MSRA. However, most of these variants are found in the intronic or intergenic regions, making it difficult to elucidate the underlying mechanisms. Therefore, in this study, we performed a whole exome sequencing of the protein-coding regions in the total genome (exome) of two obese and one normal subject belonging to the same Thai family to identify the genes responsible for obesity. We identified 709 functional variants that were differentially expressed between obese and normal subjects; of these, 65 were predicted to be deleterious to protein structure or function. The minor allele frequency of 14 of these genes (ALOX5AP, COL9A2, DEFB126, GDPD4, HCRTR1, MLL3, OPLAH, OR4C45, PRIM2, RXFP2, TIGD6, TRPM8, USP49, and ZNF596) was low, indicating causal variants that could be associated with complex traits or diseases. Genotyping revealed HCRTR1, COL9A2, and TRPM8 to be associated with the regulation of feeding behavior and energy expenditure. These genes constituted a network of pathways, including lipid metabolism, signaling transduction, immune, membrane transport, and gene regulation pathways, and seemed to play important roles in obesity.

PMID: 27421018 [PubMed - indexed for MEDLINE]

TBR1 regulates autism risk genes in the developing neocortex.

Genome Res. 2016 08;26(8):1013-22

Authors: Notwell JH, Heavner WE, Darbandi SF, Katzman S, McKenna WL, Ortiz-Londono CF, Tastad D, Eckler MJ, Rubenstein JL, McConnell SK, Chen B, Bejerano G

Abstract
Exome sequencing studies have identified multiple genes harboring de novo loss-of-function (LoF) variants in individuals with autism spectrum disorders (ASD), including TBR1, a master regulator of cortical development. We performed ChIP-seq for TBR1 during mouse cortical neurogenesis and show that TBR1-bound regions are enriched adjacent to ASD genes. ASD genes were also enriched among genes that are differentially expressed in Tbr1 knockouts, which together with the ChIP-seq data, suggests direct transcriptional regulation. Of the nine ASD genes examined, seven were misexpressed in the cortices of Tbr1 knockout mice, including six with increased expression in the deep cortical layers. ASD genes with adjacent cortical TBR1 ChIP-seq peaks also showed unusually low levels of LoF mutations in a reference human population and among Icelanders. We then leveraged TBR1 binding to identify an appealing subset of candidate ASD genes. Our findings highlight a TBR1-regulated network of ASD genes in the developing neocortex that are relatively intolerant to LoF mutations, indicating that these genes may play critical roles in normal cortical development.

PMID: 27325115 [PubMed - indexed for MEDLINE]

ZNHIT3 is defective in PEHO syndrome, a severe encephalopathy with cerebellar granule neuron loss.

Brain. 2017 Mar 01;:

Authors: Anttonen AK, Laari A, Kousi M, Yang YJ, Jääskeläinen T, Somer M, Siintola E, Jakkula E, Muona M, Tegelberg S, Lönnqvist T, Pihko H, Valanne L, Paetau A, Lun MP, Hästbacka J, Kopra O, Joensuu T, Katsanis N, Lehtinen MK, Palvimo JJ, Lehesjoki AE

Abstract
Progressive encephalopathy with oedema, hypsarrhythmia, and optic atrophy (PEHO) syndrome is an early childhood onset, severe autosomal recessive encephalopathy characterized by extreme cerebellar atrophy due to almost total granule neuron loss. By combining homozygosity mapping in Finnish families with Sanger sequencing of positional candidate genes and with exome sequencing a homozygous missense substitution of leucine for serine at codon 31 in ZNHIT3 was identified as the primary cause of PEHO syndrome. ZNHIT3 encodes a nuclear zinc finger protein previously implicated in transcriptional regulation and in small nucleolar ribonucleoprotein particle assembly and thus possibly to pre-ribosomal RNA processing. The identified mutation affects a highly conserved amino acid residue in the zinc finger domain of ZNHIT3. Both knockdown and genome editing of znhit3 in zebrafish embryos recapitulate the patients' cerebellar defects, microcephaly and oedema. These phenotypes are rescued by wild-type, but not mutant human ZNHIT3 mRNA, suggesting that the patient missense substitution causes disease through a loss-of-function mechanism. Transfection of cell lines with ZNHIT3 expression vectors showed that the PEHO syndrome mutant protein is unstable. Immunohistochemical analysis of mouse cerebellar tissue demonstrated ZNHIT3 to be expressed in proliferating granule cell precursors, in proliferating and post-mitotic granule cells, and in Purkinje cells. Knockdown of Znhit3 in cultured mouse granule neurons and ex vivo cerebellar slices indicate that ZNHIT3 is indispensable for granule neuron survival and migration, consistent with the zebrafish findings and patient neuropathology. These results suggest that loss-of-function of a nuclear regulator protein underlies PEHO syndrome and imply that establishment of its spatiotemporal interaction targets will be the basis for developing therapeutic approaches and for improved understanding of cerebellar development.

PMID: 28335020 [PubMed - as supplied by publisher]

Mutations in the leukemia inhibitory factor receptor (LIFR) gene and Lifr deficiency cause urinary tract malformations.

Hum Mol Genet. 2017 Mar 08;:

Authors: Kosfeld A, Brand F, Weiss AC, Kreuzer M, Goerk M, Martens H, Schubert S, Schäfer AK, Riehmer V, Hennies I, Bräsen JH, Pape L, Amann K, Krogvold L, Bjerre A, Daniel C, Kispert A, Haffner D, Weber RG

Abstract
Congenital anomalies of the kidneys and urinary tract (CAKUT) are the most common cause of chronic kidney disease in children. As CAKUT is a genetically heterogeneous disorder and most cases are genetically unexplained, we aimed to identify new CAKUT causing genes. Using whole-exome sequencing and trio-based de novo analysis, we identified a novel heterozygous de novo frameshift variant in the leukemia inhibitory factor receptor (LIFR) gene causing instability of the mRNA in a patient presenting with bilateral CAKUT and requiring kidney transplantation at one year of age. LIFR encodes a transmembrane receptor utilized by IL-6 family cytokines, mainly by the leukemia inhibitory factor (LIF). Mutational analysis of 121 further patients with severe CAKUT yielded two rare heterozygous LIFR missense variants predicted to be pathogenic in three unrelated patients. LIFR mutants showed decreased half-life and cell membrane localization resulting in reduced LIF-stimulated STAT3 phosphorylation. LIFR showed high expression in human fetal kidney and the human ureter, and was also expressed in the developing murine urogenital system. Lifr knockout mice displayed urinary tract malformations including hydronephrosis, hydroureter, ureter ectopia, and, consistently, reduced ureteral lumen and muscular hypertrophy, similar to the phenotypes observed in patients carrying LIFR variants. Additionally, a form of cryptorchidism was detected in all Lifr-/- mice and the patient carrying the LIFR frameshift mutation. Altogether, we demonstrate heterozygous novel or rare LIFR mutations in 3.3% of CAKUT patients, and provide evidence that Lifr deficiency and deactivating LIFR mutations cause highly similar anomalies of the urogenital tract in mice and humans.

PMID: 28334964 [PubMed - as supplied by publisher]

Clinical and genetic characterization of leukoencephalopathies in adults.

Brain. 2017 Mar 02;:

Authors: Lynch DS, Rodrigues Brandão de Paiva A, Zhang WJ, Bugiardini E, Freua F, Tavares Lucato L, Macedo-Souza LI, Lakshmanan R, Kinsella JA, Merwick A, Rossor AM, Bajaj N, Herron B, McMonagle P, Morrison PJ, Hughes D, Pittman A, Laurà M, Reilly MM, Warren JD, Mummery CJ, Schott JM, Adams M, Fox NC, Murphy E, Davagnanam I, Kok F, Chataway J, Houlden H

Abstract
Leukodystrophies and genetic leukoencephalopathies are a rare group of disorders leading to progressive degeneration of cerebral white matter. They are associated with a spectrum of clinical phenotypes dominated by dementia, psychiatric changes, movement disorders and upper motor neuron signs. Mutations in at least 60 genes can lead to leukoencephalopathy with often overlapping clinical and radiological presentations. For these reasons, patients with genetic leukoencephalopathies often endure a long diagnostic odyssey before receiving a definitive diagnosis or may receive no diagnosis at all. In this study, we used focused and whole exome sequencing to evaluate a cohort of undiagnosed adult patients referred to a specialist leukoencephalopathy service. In total, 100 patients were evaluated using focused exome sequencing of 6100 genes. We detected pathogenic or likely pathogenic variants in 26 cases. The most frequently mutated genes were NOTCH3, EIF2B5, AARS2 and CSF1R. We then carried out whole exome sequencing on the remaining negative cases including four family trios, but could not identify any further potentially disease-causing mutations, confirming the equivalence of focused and whole exome sequencing in the diagnosis of genetic leukoencephalopathies. Here we provide an overview of the clinical and genetic features of these disorders in adults.

PMID: 28334938 [PubMed - as supplied by publisher]

SLC30A9 mutation affecting intracellular zinc homeostasis causes a novel cerebro-renal syndrome.

Brain. 2017 Feb 09;:

Authors: Perez Y, Shorer Z, Liani-Leibson K, Chabosseau P, Kadir R, Volodarsky M, Halperin D, Barber-Zucker S, Shalev H, Schreiber R, Gradstein L, Gurevich E, Zarivach R, Rutter GA, Landau D, Birk OS

Abstract
A novel autosomal recessive cerebro-renal syndrome was identified in consanguineous Bedouin kindred: neurological deterioration was evident as of early age, progressing into severe intellectual disability, profound ataxia, camptocormia and oculomotor apraxia. Brain MRI was normal. Four of the six affected individuals also had early-onset nephropathy with features of tubulo-interstitial nephritis, hypertension and tendency for hyperkalemia, though none had rapid deterioration of renal function. Genome wide linkage analysis identified an ∼18 Mb disease-associated locus on chromosome 4 (maximal logarithm of odds score 4.4 at D4S2971; θ = 0). Whole exome sequencing identified a single mutation in SLC30A9 within this locus, segregating as expected within the kindred and not found in a homozygous state in 300 Bedouin controls. We showed that SLC30A9 (solute carrier family 30 member 9; also known as ZnT-9) is ubiquitously expressed with high levels in cerebellum, skeletal muscle, thymus and kidney. Confocal analysis of SH-SY5Y cells overexpressing SLC30A9 fused to enhanced green fluorescent protein demonstrated vesicular cytosolic localization associated with the endoplasmic reticulum, not co-localizing with endosomal or Golgi markers. SLC30A9 encodes a putative zinc transporter (by similarity) previously associated with Wnt signalling. However, using dual-luciferase reporter assay in SH-SY5Y cells we showed that Wnt signalling was not affected by the mutation. Based on protein modelling, the identified mutation is expected to affect SLC30A9's highly conserved cation efflux domain, putatively disrupting its transmembrane helix structure. Cytosolic Zn2+ measurements in HEK293 cells overexpressing wild-type and mutant SLC30A9 showed lower zinc concentration within mutant rather than wild-type SLC30A9 cells. This suggests that SLC30A9 has zinc transport properties affecting intracellular zinc homeostasis, and that the molecular mechanism of the disease is through defective function of this novel activity of SLC30A9 rather than by a defect in its previously described role in transcriptional activation of Wnt signalling.

PMID: 28334855 [PubMed - as supplied by publisher]

Hereditary spastic paraplegia caused by compound heterozygous mutations outside the motor domain of the KIF1A gene.

Eur J Neurol. 2017 Mar 22;:

Authors: Krenn M, Zulehner G, Hotzy C, Rath J, Stogmann E, Wagner M, Haack TB, Strom TM, Zimprich A, Zimprich F

Abstract
BACKGROUND AND PURPOSE: Hereditary spastic paraplegia is a clinically and genetically heterogeneous group of rare, inherited disorders causing an upper motor neuron syndrome with (complex) or without (pure) additional neurological symptoms. Mutations in the KIF1A gene have already been associated with recessive and dominant forms of hereditary spastic paraplegia (SPG30) in a few cases.
METHODS: All family members included in the study were examined neurologically. Whole-exome sequencing was used in affected individuals to identify the responsible candidate gene. Conventional Sanger sequencing was conducted to validate familial segregation.
RESULTS: A family of Macedonian origin with two affected siblings, one with slowly progressive and the other one with a more complex and rapidly progressing hereditary spastic paraplegia is reported. In both affected individuals, two novel pathogenic mutations outside the motor domain of the KIF1A gene were found (NM_001244008.1:c.2909G>A, p.Arg970His and c.1214dup, p.Asn405Lysfs*40) that segregate with the disease within the family establishing the diagnosis of autosomal recessive SPG30.
CONCLUSIONS: This report provides the first evidence that mutations outside the motor domain of the gene can cause (recessive) SPG30 and extends the genotype-phenotype association for KIF1A-related diseases.

PMID: 28332297 [PubMed - as supplied by publisher]

Mutations in EFL1, an SBDS partner, are associated with infantile pancytopenia, exocrine pancreatic insufficiency and skeletal anomalies in a Shwachman-Diamond like syndrome.

J Med Genet. 2017 Mar 22;:

Authors: Stepensky P, Chacón-Flores M, Kim KH, Abuzaitoun O, Bautista-Santos A, Simanovsky N, Siliqi D, Altamura D, Méndez-Godoy A, Gijsbers A, Naser Eddin A, Dor T, Charrow J, Sánchez-Puig N, Elpeleg O

Abstract
BACKGROUND: For the final step of the maturation of the ribosome, the nascent 40S and 60S subunits are exported from the nucleus to the cell cytoplasm. To prevent premature association of these ribosomal subunits, eukaryotic initiation factor 6 (eIF6) binds the 60S subunit within the nucleus. Its release in the cytoplasm requires the interaction of EFL1 and SDBS proteins. In Shwachman-Diamond syndrome (SDS), a defective SDBS protein prevents eIF6 eviction, inhibiting its recycle to the nucleus and subsequent formation of the active 80S ribosome.
OBJECTIVE: This study aims to identify the molecular basis of an SDS-like disease, manifested by pancytopenia, exocrine pancreatic insufficiency and skeletal abnormalities in six patients from three unrelated families.
METHODS: Whole exome analysis was used for mutation identification. Fluorescence microscopy studies assessed the localisation of Tif6-GFP, the yeast eIF6 homologue, in yeast WT and mutant cells. Human and yeast EFL1 proteins, WT and mutants, were expressed in Saccharomyces cerevisiae BCY123 strain, and circular dichroism and small-angle X-ray scattering were used to assess the folding and flexibility of these proteins. Green malachite colorimetric assay was performed to determine the GTPase activity of WT and Efl1 mutants.
RESULTS: Four patients were homozygous for p.R1095Q variant and two patients were homozygous for p.M882K variant in EFL1. Residue R1095 and M882 are conserved across species. Neither the GTPase activity of the mutant proteins nor its activation by the SDBD protein or the 60S ribosomal subunit were affected. Complementation of efl1Δ yeast cells with the EFL1 mutants rescued the slow growth phenotype. Nonetheless, Tif6-GFP was relocalised to the cytoplasm in mutant yeast cells in contrast to its nuclear localisation in WT cells.
CONCLUSIONS: Mutations in EFL1 clinically manifest as SDS-like phenotype. Similar to the molecular pathology of SDS, mutant EFL1 proteins do not promote the release of cytoplasmic Tif6 from the 60S subunit, likely preventing the formation of mature ribosomes.

PMID: 28331068 [PubMed - as supplied by publisher]

Personalized In Vitro and In Vivo Cancer Models to Guide Precision Medicine.

Cancer Discov. 2017 Mar 22;:

Authors: Pauli C, Hopkins BD, Prandi D, Shaw R, Fedrizzi T, Sboner A, Sailer V, Augello M, Puca L, Rosati R, McNary TJ, Churakova Y, Cheung C, Triscott J, Pisapia D, Rao R, Mosquera JM, Robinson B, Faltas BM, Emerling BE, Gadi VK, Bernard B, Elemento O, Beltran H, Demichelis F, Kemp CJ, Grandori C, Cantley LC, Rubin MA

Abstract
Precision medicine is an approach that takes into account the influence of individuals' genes, environment, and lifestyle exposures to tailor interventions. Here, we describe the development of a robust precision cancer care platform that integrates whole-exome sequencing with a living biobank that enables high-throughput drug screens on patient-derived tumor organoids. To date, 56 tumor-derived organoid cultures and 19 patient-derived xenograft (PDX) models have been established from the 769 patients enrolled in an Institutional Review Board-approved clinical trial. Because genomics alone was insufficient to identify therapeutic options for the majority of patients with advanced disease, we used high-throughput drug screening to discover effective treatment strategies. Analysis of tumor-derived cells from four cases, two uterine malignancies and two colon cancers, identified effective drugs and drug combinations that were subsequently validated using 3-D cultures and PDX models. This platform thereby promotes the discovery of novel therapeutic approaches that can be assessed in clinical trials and provides personalized therapeutic options for individual patients where standard clinical options have been exhausted.SIGNIFICANCE: Integration of genomic data with drug screening from personalized in vitro and in vivo cancer models guides precision cancer care and fuels next-generation research. Cancer Discov; 7(5); 1-16. ©2017 AACR.

PMID: 28331002 [PubMed - as supplied by publisher]

Outcomes of Diagnostic Exome Sequencing in Patients With Diagnosed or Suspected Autism Spectrum Disorders.

Pediatr Neurol. 2017 Feb 08;:

Authors: Rossi M, El-Khechen D, Black MH, Farwell Hagman KD, Tang S, Powis Z

Abstract
BACKGROUND: Exome sequencing has recently been proved to be a successful diagnostic method for complex neurodevelopmental disorders. However, the diagnostic yield of exome sequencing for autism spectrum disorders has not been extensively evaluated in large cohorts to date.
MATERIALS AND METHODS: We performed diagnostic exome sequencing in a cohort of 163 individuals with autism spectrum disorder (66.3%) or autistic features (33.7%).
RESULTS: The diagnostic yield observed in patients in our cohort was 25.8% (42 of 163) for positive or likely positive findings in characterized disease genes, while a candidate genetic etiology was reported for an additional 3.3% (4 of 120) of patients. Among the positive findings in the patients with autism spectrum disorder or autistic features, 61.9% were the result of de novo mutations. Patients presenting with psychiatric conditions or ataxia or paraplegia in addition to autism spectrum disorder or autistic features were significantly more likely to receive positive results compared with patients without these clinical features (95.6% vs 27.1%, P < 0.0001; 83.3% vs 21.2%, P < 0.0001, respectively). The majority of the positive findings were in recently identified autism spectrum disorder genes, supporting the importance of diagnostic exome sequencing for patients with autism spectrum disorder or autistic features as the causative genes might evade traditional sequential or panel testing.
CONCLUSIONS: These results suggest that diagnostic exome sequencing would be an efficient primary diagnostic method for patients with autism spectrum disorders or autistic features. Moreover, our data may aid clinicians to better determine which subset of patients with autism spectrum disorder with additional clinical features would benefit the most from diagnostic exome sequencing.

PMID: 28330790 [PubMed - as supplied by publisher]

Genomic characterisation of HER2-positive breast cancer and response to neoadjuvant trastuzumab and chemotherapy - results from the ACOSOG Z1041 (Alliance) trial.

Ann Oncol. 2017 Feb 21;:

Authors: Lesurf R, Griffith OL, Griffith M, Hundal J, Trani L, Watson MA, Aft R, Ellis MJ, Ota D, Suman VJ, Meric-Bernstam F, Leitch AM, Boughey JC, Unzeitig G, Buzdar AU, Hunt KK, Mardis ER

Abstract
Background: HER2 ( ERBB2 ) gene amplification and its corresponding overexpression are present in 15-30% of invasive breast cancers. While HER2-targeted agents are effective treatments, resistance remains a major cause of death. The American College of Surgeons Oncology Group Z1041 trial (NCT00513292) was designed to compare the pathologic complete response (pCR) rate of distinct regimens of neoadjuvant chemotherapy and trastuzumab, but ultimately identified no difference [1].
Patients and methods: In supplement to tissues from 37 Z1041 cases, 11 similarly treated cases were obtained from a single institution study (NCT00353483). We have extracted genomic DNA from both pre-treatment tumor biopsies and blood of these 48 cases, and performed whole genome (WGS) and exome sequencing. Coincident with these efforts, we have generated RNA-seq profiles from 42 of the tumor biopsies. Among patients in this cohort, 24 (50%) achieved a pCR.
Results: Here we characterized the genomic landscape of HER2-positive breast cancer and investigated associations between genomic features and pCR. Cases assigned to the HER2-enriched subtype by RNA-seq analysis were more likely to achieve a pCR compared to the luminal, basal-like, or normal-like subtypes (19/27 versus 3/15; P =0.0032). Mutational events led to the generation of putatively active neoantigens, but were overall not associated with pCR. ERBB2 and GRB7 were the genes most commonly observed in fusion events, and genomic copy number analysis of the ERBB2 locus indicated that cases with either no observable or low-level ERBB2 amplification were less likely to achieve a pCR (7/8 versus 17/40; P =0.048). Moreover, among cases that achieved a pCR, tumors consistently expressed immune signatures that may contribute to therapeutic response.
Conclusion: The identification of these features suggests that it may be possible to predict, at the time of diagnosis, those HER2-positive breast cancer patients who will not respond to treatment with chemotherapy and trastuzumab.

PMID: 28327926 [PubMed - as supplied by publisher]

Analysis of exome data for 4293 trios suggests GPI-anchor biogenesis defects are a rare cause of developmental disorders.

Eur J Hum Genet. 2017 Mar 22;:

Authors: Pagnamenta AT, Murakami Y, Taylor JM, Anzilotti C, Howard MF, Miller V, Johnson DS, Tadros S, Mansour S, Temple IK, Firth R, Rosser E, Harrison RE, Kerr B, Popitsch N, DDD Study, Kinoshita T, Taylor JC, Kini U

Abstract
Over 150 different proteins attach to the plasma membrane using glycosylphosphatidylinositol (GPI) anchors. Mutations in 18 genes that encode components of GPI-anchor biogenesis result in a phenotypic spectrum that includes learning disability, epilepsy, microcephaly, congenital malformations and mild dysmorphic features. To determine the incidence of GPI-anchor defects, we analysed the exome data from 4293 parent-child trios recruited to the Deciphering Developmental Disorders (DDD) study. All probands recruited had a neurodevelopmental disorder. We searched for variants in 31 genes linked to GPI-anchor biogenesis and detected rare biallelic variants in PGAP3, PIGN, PIGT (n=2), PIGO and PIGL, providing a likely diagnosis for six families. In five families, the variants were in a compound heterozygous configuration while in a consanguineous Afghani kindred, a homozygous c.709G>C; p.(E237Q) variant in PIGT was identified within 10-12 Mb of autozygosity. Validation and segregation analysis was performed using Sanger sequencing. Across the six families, five siblings were available for testing and in all cases variants co-segregated consistent with them being causative. In four families, abnormal alkaline phosphatase results were observed in the direction expected. FACS analysis of knockout HEK293 cells that had been transfected with wild-type or mutant cDNA constructs demonstrated that the variants in PIGN, PIGT and PIGO all led to reduced activity. Splicing assays, performed using leucocyte RNA, showed that a c.336-2A>G variant in PIGL resulted in exon skipping and p.D113fs*2. Our results strengthen recently reported disease associations, suggest that defective GPI-anchor biogenesis may explain ~0.15% of individuals with developmental disorders and highlight the benefits of data sharing.European Journal of Human Genetics advance online publication, 22 March 2017; doi:10.1038/ejhg.2017.32.

PMID: 28327575 [PubMed - as supplied by publisher]

Insights from early experience of a Rare Disease Genomic Medicine Multidisciplinary Team: a qualitative study.

Eur J Hum Genet. 2017 Mar 22;:

Authors: Ormondroyd E, Mackley MP, Blair E, Craft J, Knight JC, Taylor J, Taylor JC, Wilkie AO, Watkins H

Abstract
Whole-exome/whole-genome sequencing (WES/WGS) has the potential to enhance genetic diagnosis of rare disease, and is increasingly becoming part of routine clinical care in mainstream medicine. Effective translation will require ongoing efforts in a number of areas including: selection of appropriate patients, provision of effective consent, pre- and post-test genetic counselling, improving variant interpretation algorithms and practices, and management of secondary findings including those found incidentally and those actively sought. Allied to this is the need for an effective education programme for all members of clinical teams involved in care of patients with rare disease, as well as to maintain public confidence in the use of these technologies. We established a Genomic Medicine Multidisciplinary Team (GM-MDT) in 2014 to build on the experiences of earlier successful research-based WES/WGS studies, to address these needs and to review results including pertinent and secondary findings. Here we report on a qualitative study of decision-making in the GM-MDT combined with analysis of semi-structured interviews with GM-MDT members. Study findings show that members appreciate the clinical and scientific diversity of the GM-MDT and value it for education and oversight. To date, discussions have focussed on case selection including the extent and interpretation of clinical and family history information required to establish likely monogenic aetiology and inheritance model. Achieving a balance between effective use of WES/WGS - prioritising cases in a diverse and highly complex patient population where WES/WGS will be tractable - and meeting the recruitment targets of a large project is considered challenging.European Journal of Human Genetics advance online publication, 22 March 2017; doi:10.1038/ejhg.2017.37.

PMID: 28327571 [PubMed - as supplied by publisher]

PUF60 variants cause a syndrome of ID, short stature, microcephaly, coloboma, craniofacial, cardiac, renal and spinal features.

Eur J Hum Genet. 2017 Mar 22;:

Authors: Low KJ, Ansari M, Abou Jamra R, Clarke A, El Chehadeh S, FitzPatrick DR, Greenslade M, Henderson A, Hurst J, Keller K, Kuentz P, Prescott T, Roessler F, Selmer KK, Schneider MC, Stewart F, Tatton-Brown K, Thevenon J, Vigeland MD, Vogt J, Willems M, Zonana J, Study DD, Smithson SF

Abstract
PUF60 encodes a nucleic acid-binding protein, a component of multimeric complexes regulating RNA splicing and transcription. In 2013, patients with microdeletions of chromosome 8q24.3 including PUF60 were found to have developmental delay, microcephaly, craniofacial, renal and cardiac defects. Very similar phenotypes have been described in six patients with variants in PUF60, suggesting that it underlies the syndrome. We report 12 additional patients with PUF60 variants who were ascertained using exome sequencing: six through the Deciphering Developmental Disorders Study and six through similar projects. Detailed phenotypic analysis of all patients was undertaken. All 12 patients had de novo heterozygous PUF60 variants on exome analysis, each confirmed by Sanger sequencing: four frameshift variants resulting in premature stop codons, three missense variants that clustered within the RNA recognition motif of PUF60 and five essential splice-site (ESS) variant. Analysis of cDNA from a fibroblast cell line derived from one of the patients with an ESS variants revealed aberrant splicing. The consistent feature was developmental delay and most patients had short stature. The phenotypic variability was striking; however, we observed similarities including spinal segmentation anomalies, congenital heart disease, ocular colobomata, hand anomalies and (in two patients) unilateral renal agenesis/horseshoe kidney. Characteristic facial features included micrognathia, a thin upper lip and long philtrum, narrow almond-shaped palpebral fissures, synophrys, flared eyebrows and facial hypertrichosis. Heterozygote loss-of-function variants in PUF60 cause a phenotype comprising growth/developmental delay and craniofacial, cardiac, renal, ocular and spinal anomalies, adding to disorders of human development resulting from aberrant RNA processing/spliceosomal function.European Journal of Human Genetics advance online publication, 22 March 2017; doi:10.1038/ejhg.2017.27.

PMID: 28327570 [PubMed - as supplied by publisher]

Lessons learned from additional research analyses of unsolved clinical exome cases.

Genome Med. 2017 Mar 21;9(1):26

Authors: Eldomery MK, Coban-Akdemir Z, Harel T, Rosenfeld JA, Gambin T, Stray-Pedersen A, Küry S, Mercier S, Lessel D, Denecke J, Wiszniewski W, Penney S, Liu P, Bi W, Lalani SR, Schaaf CP, Wangler MF, Bacino CA, Lewis RA, Potocki L, Graham BH, Belmont JW, Scaglia F, Orange JS, Jhangiani SN, Chiang T, Doddapaneni H, Hu J, Muzny DM, Xia F, Beaudet AL, Boerwinkle E, Eng CM, Plon SE, Sutton VR, Gibbs RA, Posey JE, Yang Y, Lupski JR

Abstract
BACKGROUND: Given the rarity of most single-gene Mendelian disorders, concerted efforts of data exchange between clinical and scientific communities are critical to optimize molecular diagnosis and novel disease gene discovery.
METHODS: We designed and implemented protocols for the study of cases for which a plausible molecular diagnosis was not achieved in a clinical genomics diagnostic laboratory (i.e. unsolved clinical exomes). Such cases were recruited to a research laboratory for further analyses, in order to potentially: (1) accelerate novel disease gene discovery; (2) increase the molecular diagnostic yield of whole exome sequencing (WES); and (3) gain insight into the genetic mechanisms of disease. Pilot project data included 74 families, consisting mostly of parent-offspring trios. Analyses performed on a research basis employed both WES from additional family members and complementary bioinformatics approaches and protocols.
RESULTS: Analysis of all possible modes of Mendelian inheritance, focusing on both single nucleotide variants (SNV) and copy number variant (CNV) alleles, yielded a likely contributory variant in 36% (27/74) of cases. If one includes candidate genes with variants identified within a single family, a potential contributory variant was identified in a total of ~51% (38/74) of cases enrolled in this pilot study. The molecular diagnosis was achieved in 30/63 trios (47.6%). Besides this, the analysis workflow yielded evidence for pathogenic variants in disease-associated genes in 4/6 singleton cases (66.6%), 1/1 multiplex family involving three affected siblings, and 3/4 (75%) quartet families. Both the analytical pipeline and the collaborative efforts between the diagnostic and research laboratories provided insights that allowed recent disease gene discoveries (PURA, TANGO2, EMC1, GNB5, ATAD3A, and MIPEP) and increased the number of novel genes, defined in this study as genes identified in more than one family (DHX30 and EBF3).
CONCLUSION: An efficient genomics pipeline in which clinical sequencing in a diagnostic laboratory is followed by the detailed reanalysis of unsolved cases in a research environment, supplemented with WES data from additional family members, and subject to adjuvant bioinformatics analyses including relaxed variant filtering parameters in informatics pipelines, can enhance the molecular diagnostic yield and provide mechanistic insights into Mendelian disorders. Implementing these approaches requires collaborative clinical molecular diagnostic and research efforts.

PMID: 28327206 [PubMed - in process]

Whole exome sequencing with genomic triangulation implicates CDH2-encoded N-cadherin as a novel pathogenic substrate for arrhythmogenic cardiomyopathy.

Congenit Heart Dis. 2017 Mar 21;:

Authors: Turkowski KL, Tester DJ, Bos JM, Haugaa KH, Ackerman MJ

Abstract
BACKGROUND: Arrhythmogenic cardiomyopathy (ACM) is a heritable disease characterized by fibrofatty replacement of cardiomyocytes, has a prevalence of approximately 1 in 5000 individuals, and accounts for approximately 20% of sudden cardiac death in the young (≤35 years). ACM is most often inherited as an autosomal dominant trait with incomplete penetrance and variable expression. While mutations in several genes that encode key desmosomal proteins underlie about half of all ACM, the remainder is elusive genetically.
OBJECTIVE: Here, whole exome sequencing (WES) was performed with genomic triangulation in an effort to identify a novel explanation for a phenotype-positive, genotype-negative multi-generational pedigree with a presumed autosomal dominant, maternal inheritance of ACM.
METHODS: WES and genomic triangulation was performed on a symptomatic 14-year-old female proband, her affected mother and affected sister, and her unaffected father to elucidate a novel ACM-susceptibility gene for this pedigree. Following variant filtering using Ingenuity® Variant Analysis, gene priority ranking was performed on the candidate genes using ToppGene and Endeavour. The phylogenetic and physiochemical properties of candidate mutations were assessed further by 6 in silico prediction tools. Species alignment and amino acid conservation analysis was performed using the Uniprot Consortium. Tissue expression data was abstracted from Expression Atlas.
RESULTS: Following WES and genomic triangulation, CDH2 emerged as a novel, autosomal dominant, ACM-susceptibility gene. The CDH2-encoded N-cadherin is a cell-cell adhesion protein predominately expressed in the heart. Cardiac dysfunction has been demonstrated in prior CDH2 knockout and over-expression animal studies. Further in silico mutation prediction, species conservation, and protein expression analysis supported the ultra-rare (minor allele frequency <0.005%) p.Asp407Asn-CDH2 variant as a likely pathogenic variant.
CONCLUSIONS: Herein, it is demonstrated that genetic mutations in CDH2-encoded N-cadherin may represent a novel pathogenetic basis for ACM in humans. The prevalence of CDH2-mediated ACM in heretofore genetically elusive ACM remains to be determined.

PMID: 28326674 [PubMed - as supplied by publisher]

Exome Analysis of the Evolutionary Path of Hepatocellular Adenoma-Carcinoma Transition, Vascular Invasion and Brain Dissemination.

J Hepatol. 2017 Mar 17;:

Authors: Vilarinho S, Erson-Omay Z, Mitchell-Richards K, Cha C, Nelson-Williams C, Harmancı AS, Yasuno K, Günel M, Taddei TH

Abstract
Hepatocellular adenoma (HCA) is a rare benign liver tumor, predominantly seen in young women. Its major complications are malignant transformation, spontaneous hemorrhage, and rupture. We describe a case of a young female with no underlying liver disease who presented with acute abdominal pain and was found to have a 17 cm heterogeneous mass in the left lobe of the liver. She underwent left hepatectomy and pathology revealed a 14 cm moderately differentiated hepatocellular carcinoma (HCC) arising in a shell of a HCA. At that time, vascular invasion was already present. She rapidly developed recurrent multifocal hepatic lesions and subsequent spread to the brain, leading to her death 18 months after surgery. To investigate the underlying genetic events occurring during hepatocellular adenoma-carcinoma transition and extra-hepatic dissemination, we performed whole-exome sequencing of DNA isolated from peripheral blood leucocytes, HCA, HCC, tumor thrombus and brain metastasis. Our data show a step-wise addition of somatic mutations and copy number variations with disease progression, suggesting a linear tumor evolution, which is supported by clonality analysis. Specifically, using a model based clustering of somatic mutations, one single founding clone arising in the HCA, which included CTNNB1 and IL6ST driver mutations, was identified and displayed an increasing clonality rate in HCC, tumor thrombus and brain metastasis. Our data highlight the feasibility of performing whole-exome capture, sequencing and analysis using FFPE samples, and we describe the first genomic longitudinal study of hepatocellular adenoma-carcinoma transition, vascular invasion and brain metastasis with detailed clinicopathologic annotation.

PMID: 28323122 [PubMed - as supplied by publisher]

A novel aberrant splice site mutation in COL27A1 is responsible for Steel syndrome and extension of the phenotype to include hearing loss.

Am J Med Genet A. 2017 Mar 21;:

Authors: Gariballa N, Ben-Mahmoud A, Komara M, Al-Shamsi AM, John A, Ali BR, Al-Gazali L

Abstract
Steel syndrome is an autosomal recessive disease characterized by skeletal abnormalities and dysmorphic features. The first mutation associated with this syndrome was reported in Puerto Rican children. In this study, we identified a novel homozygous splice site variant in COL27A1 (c.3556-2A>G) in a consanguineous Emirati family with a child affected by Steel syndrome. In addition, the affected child had severe non-progressive sensorineural hearing loss not reported previously. The variant segregated in the family in an autosomal recessive manner and we show that the variant alters mRNA splicing. Furthermore, relative quantitative analysis revealed a marked reduction in gene expression in the proposita compared to healthy controls. Segregation analysis of heterozygous variants, related to hearing loss, identified by whole exome sequencing in the child (ILDR1: c.1159T>C, SYNE4: c.313G>C, and GPR98: c.18746T>G) excluded them from being responsible for the hearing loss in the proposita. In addition, the products of these genes are not interacting in the same pathway and have only been reported to cause deafness in an autosomal recessive manner. Therefore, we conclude that the novel splice-site variant identified in COL27A1 is the most likely cause for Steel syndrome in this family and that the hearing loss is part of this syndrome's phenotype.

PMID: 28322503 [PubMed - as supplied by publisher]