Excessive burden of lysosomal storage disorder gene variants in Parkinson's disease.

Brain. 2017 Nov 13;:

Authors: Robak LA, Jansen IE, van Rooij J, Uitterlinden AG, Kraaij R, Jankovic J, International Parkinson’s Disease Genomics Consortium (IPDGC), Heutink P, Shulman JM, IPDGC Consortium members, International Parkinson’s Disease Genomics Consortium (IPDGC)

Abstract
Mutations in the glucocerebrosidase gene (GBA), which cause Gaucher disease, are also potent risk factors for Parkinson's disease. We examined whether a genetic burden of variants in other lysosomal storage disorder genes is more broadly associated with Parkinson's disease susceptibility. The sequence kernel association test was used to interrogate variant burden among 54 lysosomal storage disorder genes, leveraging whole exome sequencing data from 1156 Parkinson's disease cases and 1679 control subjects. We discovered a significant burden of rare, likely damaging lysosomal storage disorder gene variants in association with Parkinson's disease risk. The association signal was robust to the exclusion of GBA, and consistent results were obtained in two independent replication cohorts, including 436 cases and 169 controls with whole exome sequencing and an additional 6713 cases and 5964 controls with exome-wide genotyping. In secondary analyses designed to highlight the specific genes driving the aggregate signal, we confirmed associations at the GBA and SMPD1 loci and newly implicate CTSD, SLC17A5, and ASAH1 as candidate Parkinson's disease susceptibility genes. In our discovery cohort, the majority of Parkinson's disease cases (56%) have at least one putative damaging variant in a lysosomal storage disorder gene, and 21% carry multiple alleles. Our results highlight several promising new susceptibility loci and reinforce the importance of lysosomal mechanisms in Parkinson's disease pathogenesis. We suggest that multiple genetic hits may act in combination to degrade lysosomal function, enhancing Parkinson's disease susceptibility.

PMID: 29140481 [PubMed - as supplied by publisher]

Genetic mutational testing of Chinese children with familial hematuria with biopsy‑proven FSGS.

Mol Med Rep. 2017 Nov 10;:

Authors: Li Y, Wang Y, He Q, Dang X, Cao Y, Wu X, Mo S, He X, Yi Z

Abstract
Focal segmental glomerulosclerosis (FSGS) is a pathological lesion rather than a disease, with a diverse etiology. FSGS may result from genetic and non‑genetic factors. FSGS is considered a podocyte disease due to the fact that in the majority of patients with proven‑FSGS, the lesion results from defects in the podocyte structure or function. However, FSGS does not result exclusively from podocyte‑associated genes, however also from other genes including collagen IV‑associated genes. Patients who carry the collagen type IVA3 chain (COL4A3) or COL4A4 mutations usually exhibit Alport Syndrome (AS), thin basement membrane neuropathy or familial hematuria (FH). Previous studies revealed that long‑time persistent microscopic hematuria may lead to FSGS. A case of a family is presented here where affected individuals exhibited FH with FSGS‑proven, or chronic kidney disease. Renal biopsies were unhelpful and failed to demonstrate glomerular or basement membrane defects consistent with an inherited glomerulopathy, and therefore a possible underlying genetic cause for a unifying diagnosis was pursued. Genomic DNA of the siblings affected by FH with biopsy‑proven FSGS was analyzed, and their father was screened for 18 gene mutations associated with FSGS [nephrin, podocin, CD2 associated protein, phospholipase C ε, actinin α 4, transient receptor potential cation channel subfamily C member 6, inverted formin, FH2 and WH2 domain containing, Wilms tumor 1, LIM homeobox transcription factor 1 β, laminin subunit β 2, laminin subunit β 3, galactosida α, integrin subunit β 4, scavenger receptor class B member 2, coenzyme Q2, decaprenyl diphosphate synthase subunit 2, mitochondrially encoded tRNA leucine 1 (UUA/G; TRNL1) and SWI/SNF related, matrix associated, actin dependent regulator of chromatin, subfamily a like 1] using matrix‑assisted laser desorption/ionization time‑of‑flight mass spectrometry technology. Then whole exome sequencing (WES) was performed in the two probands to ascertain whether there were other known or unknown gene mutations that segregated with the disease. Using mass array technology, a TRNL1 missense homozygous mutation (m. 3290T>C) was identified in the probands diagnosed with FH and manifested as FSGS on biopsy. In addition, a COL4A4 missense mutation c. 4195A>T (p. M1399L) in heterozygous pattern was identified using WES. None of these variants were detected in their father. In the present study, a mutation in TRNL1 (m. 3290T>C) was identified, which was the first reported variant associated with FSGS. The COL4A4 (c. 4195A>T) may co‑segregate with FSGS. Screening for COL4A mutations in familial FSGS patients is suggested in the present study. Genetic investigations of families with similar clinical phenotypes should be a priority for nephrologists. The combination of mass array technology and WES may improve the detection rate of genetic mutation with a high level of accuracy.

PMID: 29138824 [PubMed - as supplied by publisher]

Beyond ALS and FTD: the phenotypic spectrum of TBK1 mutations includes PSP-like and cerebellar phenotypes.

Neurobiol Aging. 2017 Oct 24;:

Authors: Wilke C, Baets J, De Bleecker JL, Deconinck T, Biskup S, Hayer SN, Züchner S, Schüle R, De Jonghe P, Synofzik M

Abstract
Mutations in the TANK-binding kinase 1 gene (TBK1) are a rare, but recurrent cause of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). However, the complete phenotypic spectrum of syndromes associated with TBK1 mutations remains to be elucidated. Using next-generation panel-sequencing of neurodegenerative disease genes, we identified a TBK1 index patient presenting with a progressive supranuclear palsy-like syndrome. Consecutively, we screened the whole-exome sequencing data of 439 index subjects presenting with various neurodegenerative syndromes outside the ALS-FTD spectrum for TBK1 mutations. Based on this genetic screen, we identified another TBK1 index patient presenting with progressive cerebellar ataxia. Both index patients carried the established p.Glu643del TBK1 mutation (c.1928_1930delAAG). In the index patients' families, we identified mesencephalic and cerebellar atrophy as recurrent imaging findings of TBK1-associated neurodegeneration, with cerebellar atrophy occurring even in presymptomatic mutation carriers. Our findings demonstrate that the phenotypic spectrum of TBK1 mutations extends beyond ALS and FTD to include also progressive supranuclear palsy-like and cerebellar syndromes, with mesencephalon and cerebellum representing recurrent sites of TBK1-associated neurodegeneration.

PMID: 29137817 [PubMed - as supplied by publisher]

Clinical delineation of a subtype of frontonasal dysplasia with creased nasal ridge and upper limb anomalies: Report of six unrelated patients.

Am J Med Genet A. 2017 Dec;173(12):3136-3142

Authors: Lehalle D, Altunoglu U, Bruel AL, Arnaud E, Blanchet P, Choi JW, Désir J, Kiliç E, Lederer D, Pinson L, Thauvin-Robinet C, Singer A, Thevenon J, Callier P, Kayserili H, Faivre L

Abstract
Frontonasal dysplasias are rare congenital malformations of frontonasal process-derived structures, characterized by median cleft, nasal anomalies, widely spaced eyes, and cranium bifidum occultum. Several entities of syndromic frontonasal dysplasia have been described, among which, to date, only a few have identified molecular bases. We clinically ascertained a cohort of 124 individuals referred for frontonasal dysplasia. We identified six individuals with a similar phenotype, including one discordant monozygous twin. Facial features were remarkable by nasal deformity with creased ridge and depressed or absent tip, widely spaced eyes, almond-shaped palpebral fissures, and downturned corners of the mouth. All had apparently normal psychomotor development. In addition, upper limb anomalies, frontonasal encephalocele, corpus callosum agenesis, choanal atresia, and congenital heart defect were observed. We identified five reports in the literature of patients presenting with the same phenotype. Exome sequencing was performed on DNA extracted from blood of two individuals, no candidate gene was identified. In conclusion, we report six novel simplex individuals presenting with a specific frontonasal dysplasia entity associating recognizable facial features, limb and visceral malformations, and apparently normal development. The identification of discordant monozygotic twins supports the hypothesis of a mosaic disorder. Although previous patients have been reported, this is the first series, allowing delineation of a clinical subtype of frontonasal dysplasia, paving the way toward the identification of its molecular etiology.

PMID: 29136349 [PubMed - in process]

Genome-wide sequencing expands the phenotypic spectrum of EP300 variants.

Eur J Med Genet. 2017 Nov 10;:

Authors: Costain G, Kannu P, Bowdin S

Abstract
Many disease genes are defined by their role in causing specific clinically recognizable syndromes. Heterozygous loss of function of the gene EP300 is responsible for a minority of cases of Rubinstein-Taybi syndrome (RSTS). With the application of whole-exome sequencing and whole-genome sequencing, there is the potential to discover new genotype-phenotype correlations. The purpose of this case series is to describe three unrelated females without classic manifestations of RSTS who were unexpectedly found on genome-wide sequencing to have likely pathogenic variants in EP300. These individuals expand our knowledge of the disease spectrum by virtue of their very rare or novel clinical features, including hyperinsulinism. Results are placed within the context of all prior published EP300 cases not ascertained by targeted testing, which are disproportionately female compared with a cohort identified because of a clinical suspicion of RSTS (p = 0.01). There are implications for diagnosis, management, and genetic counselling of individuals with EP300-related disease.

PMID: 29133209 [PubMed - as supplied by publisher]

Homozygous loss of function BRCA1 variant causing a fanconi-anemia-like phenotype, a clinical report and review of previous patients.

Eur J Med Genet. 2017 Nov 10;:

Authors: Freire BL, Homma TK, Funari MFA, Lerario AM, de Medeiros Leal A, Rodrigues Pereira Velloso ED, Malaquias AC, Jorge AAL

Abstract
BACKGROUND: Fanconi Anemia (FA) is a rare and heterogeneous genetic syndrome. It is associated with short stature, bone marrow failure, high predisposition to cancer, microcephaly and congenital malformation. Many genes have been associated with FA. Previously, two adult patients with biallelic pathogenic variant in Breast Cancer 1 gene (BRCA1) had been identified in Fanconi Anemia-like condition.
CLINICAL REPORT: The proband was a 2.5 year-old girl with severe short stature, microcephaly, neurodevelopmental delay, congenital heart disease and dysmorphic features. Her parents were third degree cousins. Routine screening tests for short stature was normal.
METHODS: We conducted whole exome sequencing (WES) of the proband and used an analysis pipeline to identify rare nonsynonymous genetic variants that cause short stature.
RESULTS: We identified a homozygous loss-of-function BRCA1 mutation (c.2709T > A; p. Cys903*), which promotes the loss of critical domains of the protein. Cytogenetic study with DEB showed an increased chromosomal breakage. We screened heterozygous parents of the index case for cancer and we detected, in her mother, a metastatic adenocarcinoma in an axillar lymph node with probable primary site in the breast.
CONCLUSION: It is possible to consolidate the FA-like phenotype associated with biallelic loss-of-function BRCA1, characterized by microcephaly, short stature, developmental delay, dysmorphic face features and cancer predisposition. In our case, the WES allowed to establish the genetic cause of short stature in the context of a chromosome instability syndrome. An identification of BRCA1 mutations in our patient allowed precise genetic counseling and also triggered cancer screening for the patient and her family members.

PMID: 29133208 [PubMed - as supplied by publisher]

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(exome OR "exome sequencing") AND disease

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13 new pubmed citations were retrieved for your search. Click on the search hyperlink below to display the complete search results:

(exome OR "exome sequencing") AND disease

These pubmed results were generated on 2017/11/14

PubMed comprises more than millions of citations for biomedical literature from MEDLINE, life science journals, and online books. Citations may include links to full-text content from PubMed Central and publisher web sites.

MEGF10 related myopathies: A new case with adult onset disease with prominent respiratory failure and review of reported phenotypes.

Neuromuscul Disord. 2017 Oct 12;:

Authors: Harris E, Marini-Bettolo C, Töpf A, Barresi R, Polvikovski T, Bailey G, Charlton R, Tellez J, MacArthur D, Guglieri M, Lochmüller H, Bushby K, Straub V

Abstract
Recessive mutations in MEGF10 (multiple epidermal growth factor 10) have been reported in a severe early onset disorder named Early Myopathy, Areflexia, Respiratory Distress and Dysphagia, and a milder form with cores in the muscle biopsy; and a possible genotype-phenotype correlation determining the clinical presentation has been suggested. We undertook exome sequencing in a 66 year old male with a 20 year history of progressive proximal and distal weakness of upper and lower limbs, facial weakness and dysphagia, who developed respiratory failure requiring ventilation while still ambulant in his 50s. Muscle biopsy demonstrated myopathic changes with aggregation of myofibrillar proteins. Mutations in MEGF10 were identified: a novel essential splice site (c.1426+1G>T) and a novel missense variant (c.352T>C, p.(Cys118Arg)). We performed a detailed review of all reported MEGF10 cases (n = 20), and confirmed the presence of a genotype-phenotype correlation, namely that with ≥1 null mutation onset of respiratory dysfunction occurs in the first year of life, whereas with 2 missense mutations, respiratory dysfunction occurs at 10 years old or much later, as in the patient reported here. Our findings expand the phenotype of MEGF10 mutations to include onset in the 5th decade, and discuss the spectrum of MEGF10 related disease.

PMID: 29128256 [PubMed - as supplied by publisher]

A Brazilian family with inclusion body myopathy associated with Paget's disease of bone and frontotemporal dementia linked to the VCP pGly97Glu mutation.

Clin Rheumatol. 2017 Nov 10;:

Authors: Shinjo SK, Oba-Shinjo SM, Lerario AM, Marie SKN

Abstract
The objective of this study is to report a Brazilian patient and his family with inclusion body myopathy associated with Paget's disease of bone and frontotemporal dementia (IBMPFD). A systematic review of the literature on the valosin-containing protein (VCP) mutation was also performed. The proband (patient) was initially treated as a case of possible refractory polymyositis with Paget's disease and later as an inclusion body myopathy. However, after admission to our service, and considering his personal and familial antecedents, whole exome sequencing was performed revealing valosin-containing protein (VCP) c.290G>A (p.Gly97Glu) mutation in the patient and his nine family members. The clinical presentation of the patient and his family was characterized by different degrees and evaluations of IBMPFD. According to the literature, only one family (Chinese) has this same VCP mutation concomitantly with different IBMPFD phenotype manifestations. The present study shows that IBMPFD should be considered as a differential diagnosis in patients with inflammatory myopathies associated to bone disease and/or cognitive impairment. Moreover, the study expands the genotypic spectrum of missense mutations of VCP gene in a Brazilian family with variable phenotypes.

PMID: 29127544 [PubMed - as supplied by publisher]

Whole Exome Sequencing of Patients with Steroid-Resistant Nephrotic Syndrome.

Clin J Am Soc Nephrol. 2017 Nov 10;:

Authors: Warejko JK, Tan W, Daga A, Schapiro D, Lawson JA, Shril S, Lovric S, Ashraf S, Rao J, Hermle T, Jobst-Schwan T, Widmeier E, Majmundar AJ, Schneider R, Gee HY, Schmidt JM, Vivante A, van der Ven AT, Ityel H, Chen J, Sadowski CE, Kohl S, Pabst WL, Nakayama M, Somers MJG, Rodig NM, Daouk G, Baum M, Stein DR, Ferguson MA, Traum AZ, Soliman NA, Kari JA, El Desoky S, Fathy H, Zenker M, Bakkaloglu SA, Müller D, Noyan A, Ozaltin F, Cadnapaphornchai MA, Hashmi S, Hopcian J, Kopp JB, Benador N, Bockenhauer D, Bogdanovic R, Stajić N, Chernin G, Ettenger R, Fehrenbach H, Kemper M, Munarriz RL, Podracka L, Büscher R, Serdaroglu E, Tasic V, Mane S, Lifton RP, Braun DA, Hildebrandt F

Abstract
BACKGROUND AND OBJECTIVES: Steroid-resistant nephrotic syndrome overwhelmingly progresses to ESRD. More than 30 monogenic genes have been identified to cause steroid-resistant nephrotic syndrome. We previously detected causative mutations using targeted panel sequencing in 30% of patients with steroid-resistant nephrotic syndrome. Panel sequencing has a number of limitations when compared with whole exome sequencing. We employed whole exome sequencing to detect monogenic causes of steroid-resistant nephrotic syndrome in an international cohort of 300 families.
DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: Three hundred thirty-five individuals with steroid-resistant nephrotic syndrome from 300 families were recruited from April of 1998 to June of 2016. Age of onset was restricted to <25 years of age. Exome data were evaluated for 33 known monogenic steroid-resistant nephrotic syndrome genes.
RESULTS: In 74 of 300 families (25%), we identified a causative mutation in one of 20 genes known to cause steroid-resistant nephrotic syndrome. In 11 families (3.7%), we detected a mutation in a gene that causes a phenocopy of steroid-resistant nephrotic syndrome. This is consistent with our previously published identification of mutations using a panel approach. We detected a causative mutation in a known steroid-resistant nephrotic syndrome gene in 38% of consanguineous families and in 13% of nonconsanguineous families, and 48% of children with congenital nephrotic syndrome. A total of 68 different mutations were detected in 20 of 33 steroid-resistant nephrotic syndrome genes. Fifteen of these mutations were novel. NPHS1, PLCE1, NPHS2, and SMARCAL1 were the most common genes in which we detected a mutation. In another 28% of families, we detected mutations in one or more candidate genes for steroid-resistant nephrotic syndrome.
CONCLUSIONS: Whole exome sequencing is a sensitive approach toward diagnosis of monogenic causes of steroid-resistant nephrotic syndrome. A molecular genetic diagnosis of steroid-resistant nephrotic syndrome may have important consequences for the management of treatment and kidney transplantation in steroid-resistant nephrotic syndrome.

PMID: 29127259 [PubMed - as supplied by publisher]

Homozygous mutation in CEP19, a gene mutated in morbid obesity, in Bardet-Biedl syndrome with predominant postaxial polydactyly.

J Med Genet. 2017 Nov 10;:

Authors: Yıldız Bölükbaşı E, Mumtaz S, Afzal M, Woehlbier U, Malik S, Tolun A

Abstract
BACKGROUND: Bardet-Biedl syndrome (BBS) is a ciliopathy with extensive phenotypic variability and genetic heterogeneity. We aimed to discover the gene mutated in a consanguineous kindred with multiple cases of a BBS phenotype.
METHODS: SNP genotype data were used for linkage analysis and exome sequencing to identify mutations. Modelling and in silico analysis were performed to predict mutation severity.
RESULTS: Patients had postaxial polydactyly plus variable other clinical features including rod-cone dystrophy, obesity, intellectual disability, renal malformation, developmental delay, dental anomalies, speech disorder and enlarged fatty liver. The 4.57 Mb disease locus harboured homozygous, truncating CEP19 c.194_195insA (p.Tyr65*) mutation. We also found glioma-associated oncogene homolog 1(GLI1) c.820G>C (p.Gly274Arg) in the homozygous state in most patients. In silico modelling strongly suggests that it is damaging. Also, different combinations of four possible modifier alleles in BBS-related genes were detected. Two are known modifier alleles for BBS, splicing variant CCDC28B c.330C>T and missense MKKS/BBS6 p.Ile339Val, and the others are C8ORF37/BBS21 p.Ala178Val and TMEM67/BBS14 modifier p.Asp799Asp. Some patients carry all those five known/possible modifier alleles. Such variants are highly significantly more abundant in our patients than in a control group.
CONCLUSION: CEP19 encodes a centrosomal and ciliary protein, as all BBS genes do. Another truncating mutation p.Arg82* has been reported as responsible for morbid obesity in a family; however, in the family we present, not all homozygotes are obese, although some are severely obese. The variant in GLI1, encoding a transcription factor that localises to the primary cilium and nucleus and is a mediator of the sonic hedgehog pathway, possibly exacerbates disease severity when in the homozygous state.

PMID: 29127258 [PubMed - as supplied by publisher]

Disruption of Thrombocyte and T Lymphocyte Development by a Mutation in ARPC1B.

J Immunol. 2017 Nov 10;:

Authors: Somech R, Lev A, Lee YN, Simon AJ, Barel O, Schiby G, Avivi C, Barshack I, Rhodes M, Yin J, Wang M, Yang Y, Rhodes J, Marcus N, Garty BZ, Stein J, Amariglio N, Rechavi G, Wiest DL, Zhang Y

Abstract
Regulation of the actin cytoskeleton is crucial for normal development and function of the immune system, as evidenced by the severe immune abnormalities exhibited by patients bearing inactivating mutations in the Wiskott-Aldrich syndrome protein (WASP), a key regulator of actin dynamics. WASP exerts its effects on actin dynamics through a multisubunit complex termed Arp2/3. Despite the critical role played by Arp2/3 as an effector of WASP-mediated control over actin polymerization, mutations in protein components of the Arp2/3 complex had not previously been identified as a cause of immunodeficiency. Here, we describe two brothers with hematopoietic and immunologic symptoms reminiscent of Wiskott-Aldrich syndrome (WAS). However, these patients lacked mutations in any of the genes previously associated with WAS. Whole-exome sequencing revealed a homozygous 2 bp deletion, n.c.G623DEL-TC (p.V208VfsX20), in Arp2/3 complex component ARPC1B that causes a frame shift resulting in premature termination. Modeling of the disease in zebrafish revealed that ARPC1B plays a critical role in supporting T cell and thrombocyte development. Moreover, the defects in development caused by ARPC1B loss could be rescued by the intact human ARPC1B ortholog, but not by the p.V208VfsX20 variant identified in the patients. Moreover, we found that the expression of ARPC1B is restricted to hematopoietic cells, potentially explaining why a mutation in ARPC1B has now been observed as a cause of WAS, whereas mutations in other, more widely expressed, components of the Arp2/3 complex have not been observed.

PMID: 29127144 [PubMed - as supplied by publisher]

Identification of CDC42BPG as a novel susceptibility locus for hyperuricemia in a Japanese population.

Mol Genet Genomics. 2017 Nov 09;:

Authors: Yasukochi Y, Sakuma J, Takeuchi I, Kato K, Oguri M, Fujimaki T, Horibe H, Yamada Y

Abstract
Chronic kidney disease and hyperuricemia are serious global health problems. Recent genome-wide association studies have identified various genetic variants related to these disorders. However, most studies have been conducted in a cross-sectional manner. To identify novel susceptibility loci for chronic kidney disease or hyperuricemia, we performed longitudinal exome-wide association studies (EWASs), using ~ 244,000 genetic variants and clinical data of Japanese individuals who had undergone annual health checkups for several years. After establishing quality controls, the association of renal function-related traits in 5648 subjects (excluding patients with dialysis and population outliers) with 24,579 single nucleotide variants (SNVs) for three genetic models (P < 3.39 × 10(- 7)) was tested using generalized estimating equation models. The longitudinal EWASs revealed novel relations of five SNVs to renal function-related traits. Cross-sectional data for renal function-related traits in 7699 Japanese subjects were examined in a replication study. Among the five SNVs, rs55975541 in CDC42BPG was significantly (P < 4.90 × 10(- 4)) related to the serum concentration of uric acid in the replication cohort. We also examined the SNVs detected in our longitudinal EWASs with the information on P values in GKDGEN meta-analysis data. Four SNVs in SLC15A2 were significantly associated with the estimated glomerular filtration rate in European ancestry populations, although these SNVs were related to the serum concentration of uric acid with borderline significance in our longitudinal EWASs. Our findings indicate that CDC42BPG may be a novel susceptibility locus for hyperuricemia.

PMID: 29124443 [PubMed - as supplied by publisher]

Sensitivity of whole exome sequencing in detecting infantile- and late-onset Pompe disease.

Mol Genet Metab. 2017 Oct 17;:

Authors: Mori M, Haskell G, Kazi Z, Zhu X, DeArmey SM, Goldstein JL, Bali D, Rehder C, Cirulli ET, Kishnani PS

Abstract
Pompe disease is a metabolic myopathy with a wide spectrum of clinical presentation. The gold-standard diagnostic test is acid alpha-glucosidase assay on skin fibroblasts, muscle or blood. Identification of two GAA pathogenic variants in-trans is confirmatory. Optimal effectiveness of enzyme replacement therapy hinges on early diagnosis, which is challenging in late-onset form of the disease due to non-specific presentation. Next-generation sequencing-based panels effectively facilitate diagnosis, but the sensitivity of whole-exome sequencing (WES) in detecting pathogenic GAA variants remains unknown. We analyzed WES data from 93 patients with confirmed Pompe disease and GAA genotypes based on PCR/Sanger sequencing. After ensuring that the common intronic variant c.-32-13T>G is not filtered out, whole-exome sequencing identified both GAA pathogenic variants in 77/93 (83%) patients. However, one variant was missed in 14/93 (15%), and both variants were missed in 2/93 (2%). One complex indel leading to a severe phenotype was incorrectly called a nonsynonymous substitution c.-32-13T>C due to misalignment. These results demonstrate that WES may fail to diagnose Pompe disease. Clinicians need to be aware of limitations of WES, and consider tests specific to Pompe disease when WES does not provide a diagnosis in patients with proximal myopathy, progressive respiratory failure or other subtle symptoms.

PMID: 29122469 [PubMed - as supplied by publisher]

Efficacy and safety of trametinib in Japanese patients with advanced biliary tract cancers refractory to gemcitabine.

Cancer Sci. 2017 Nov 09;:

Authors: Ikeda M, Ioka T, Fukutomi A, Morizane C, Kasuga A, Takahashi H, Todaka A, Okusaka T, Creasy CL, Gorman S, Felitsky DJ, Kobayashi M, Zhang F, Furuse J

Abstract
Gemcitabine-based therapy remains the mainstay of treatment for patients with biliary tract cancers (BTCs) with no second-line treatment(s) established yet. Aberrant activation of MAPK pathway in patients with BTC indicates its importance in BTC. Trametinib is a potent, highly selective, allosteric non-competitive inhibitor of MEK1/MEK2. In this Phase IIa open-label, single-arm study, we investigated efficacy and safety of trametinib in Japanese patients with advanced BTC refractory to gemcitabine-based therapy. All patients received oral trametinib 2 mg once daily until progressive disease (PD), death, or unacceptable toxicity. The primary objective was to determine the 12-week non-PD rate. Secondary assessments included safety, progression-free survival (PFS), overall survival (OS), and overall response rate. Targeted exome sequencing was performed to identify biomarkers for sensitivity or resistance to trametinib monotherapy. Twenty patients (median age, 61.5 years) with carcinoma of gall bladder (40%), intrahepatic (25%) or extrahepatic (30%) bile duct, and ampulla of Vater (5%) were enrolled. The non-PD rate at Week 12 was 10% (95% confidence interval [CI], 1.2-31.7); it did not reach the threshold rate of 25%. Median PFS was 10.6 weeks (95% CI, 4.6-12.1) and 1-year OS was 20.0%. Stable disease and PD were observed in 13 (65%) and seven (35%) patients, respectively. No new safety signals were reported. Although the primary endpoint was not met, prolonged PFS was observed in one patient having six somatic variants including synonymous NF1 exon 12 splice variant and a loss-of-function variant in ARID1A. Efforts to understand responsive mutations and sensitivity to targeted therapies are warranted. This article is protected by copyright. All rights reserved.

PMID: 29121415 [PubMed - as supplied by publisher]

De novo variants in the alternative exon 5 of SCN8A cause epileptic encephalopathy.

Genet Med. 2017 Oct 02;:

Authors: Epilepsy Genetics Initiative

Abstract
PurposeAs part of the Epilepsy Genetics Initiative, we re-evaluated clinically generated exome sequence data from 54 epilepsy patients and their unaffected parents to identify molecular diagnoses not provided in the initial diagnostic interpretation.MethodsWe compiled and analyzed exome sequence data from 54 genetically undiagnosed trios using a validated analysis pipeline. We evaluated the significance of the genetic findings by reanalyzing sequence data generated at Ambry Genetics, and from a number of additional case and control cohorts.ResultsIn 54 previously undiagnosed trios, we identified two de novo missense variants in SCN8A in the highly expressed alternative exon 5 A-an exon only recently added to the Consensus Coding Sequence database. One additional undiagnosed epilepsy patient harboring a de novo variant in exon 5 A was found in the Ambry Genetics cohort. Missense variants in SCN8A exon 5 A are extremely rare in the population, further supporting the pathogenicity of the de novo alterations identified.ConclusionThese results expand the range of SCN8A variants in epileptic encephalopathy patients and illustrate the necessity of ongoing reanalysis of negative exome sequences, as advances in the knowledge of disease genes and their annotations will permit new diagnoses to be made.GENETICS in MEDICINE advance online publication, 2 October 2017; doi:10.1038/gim.2017.100.

PMID: 29121005 [PubMed - as supplied by publisher]

A novel nonsense variant in REEP6 is involved in a sporadic rod-cone dystrophy case.

Clin Genet. 2017 Nov 09;:

Authors: Méjécase C, Mohand-Saïd S, El Shamieh S, Antonio A, Condroyer C, Blanchard S, Letexier M, Saraiva JP, Sahel JA, Audo I, Zeitz C

Abstract
Rod-cone dystrophy (RCD), also called retinitis pigmentosa, is the most common form of progressive inherited retinal disorders secondary to photoreceptor degeneration. It is a genetically heterogeneous disease characterized by night blindness, followed by visual field constriction and, in most severe cases, total blindness. The aim of our study was to identify the underlying gene defect leading to severe RCD in a 60-year-old woman. The patient's DNA was investigated by targeted next generation sequencing followed by whole exome sequencing. A novel nonsense variant, c.267G>A p.(Trp89*), was identified at a homozygous state in the proband in REEP6 gene, recently reported mutated in seven unrelated families with RCD. Further functional studies will help to understand the physiopathology associated with REEP6 mutations that may be linked to a protein trafficking defect.

PMID: 29120066 [PubMed - as supplied by publisher]

A Rare Variant in PGAP2 Causes Autosomal Recessive Hyperphosphatasia with Mental Retardation Syndrome, with a Mild Phenotype in Heterozygous Carriers.

Biomed Res Int. 2017;2017:3470234

Authors: Perez Y, Wormser O, Sadaka Y, Birk R, Narkis G, Birk OS

Abstract
Mutations in genes involved in the biosynthesis of the glycosylphosphatidylinositol (GPI) anchor cause autosomal recessive glycosylation defects, with a wide phenotypic spectrum of intellectual disability, seizures, minor facial dysmorphism, hypotonia, and elevated serum alkaline phosphatase. We now describe consanguineous Bedouin kindred presenting with an autosomal recessive syndrome of intellectual disability and elevated serum alkaline phosphatase. Genome-wide linkage analysis identified 6 possible disease-associated loci. Whole-exome sequencing followed by Sanger sequencing validation identified a single variant in PGAP2 as the disease-causing mutation (C.554G>A; p.185(R>Q)), segregating as expected within the kindred and not found in 150 Bedouin controls. The mutation replaces a highly conserved arginine residue with glutamine within the Frag1 (FGF receptor activating) domain of PGAP2. Interestingly, this mutation is a known dbSNP variant (rs745521288, build 147) with a very low allele frequency (0.00000824 in dbSNP, no homozygotes reported), highlighting the fact that dbSNP variants should not be automatically ruled out as disease-causing mutations. We further showed that PGAP2 is ubiquitously expressed, but in line with the disease phenotype, it is highly transcribed in human brain, skeletal muscle, and liver. Interestingly, a mild phenotype of slightly elevated serum levels of alkaline phosphatase and significant learning disabilities was observed in heterozygous carriers.

PMID: 29119105 [PubMed - in process]

The genomic landscape of malignant peripheral nerve sheath tumors: diverse drivers of Ras pathway activation.

Sci Rep. 2017 Nov 08;7(1):14992

Authors: Brohl AS, Kahen E, Yoder SJ, Teer JK, Reed DR

Abstract
Malignant peripheral nerve sheath tumor (MPNST) is an aggressive soft tissue sarcoma. To more fully characterize the genomic landscape of this tumor type, we performed next generation sequencing studies for mutational and copy number analysis. We analyzed whole exome sequencing data from 12 MPNST and SNP arrays for a subset of these. We additionally conducted a literature review of prior next generation sequencing studies in this disease and compared to the current study. We report recurrent mutations in NF1, SUZ12, EED, TP53 and CDKN2A in our study cohort. Combined with prior studies, we calculate the disease specific incidence of mutation in these genes to be: NF1 (56/64 = 87.5%). SUZ12 (69/123 = 56.1%), EED (40/123 = 32.5%), TP53 (29/72 = 40.3%), and CDKN2A (54/72 = 75.0%). Notably, we also identified frequent Ras pathway activating somatic mutations outside of these previously reported recurrently mutated genes. Five of the 12 MPNST in our cohort (42%) contained such a mutation. In conclusion, our study adds to the growing understanding of the genomic complexity of MPNST. We report a previously underappreciated frequency and variety of secondary or tertiary Ras pathway activating mutations, though not highly recurrent in a single gene.

PMID: 29118384 [PubMed - in process]