Frequent genes in rare diseases: panel-based next generation sequencing to disclose causal mutations in hereditary neuropathies.

J Neurochem. 2017 Dec;143(5):507-522

Authors: Dohrn MF, Glöckle N, Mulahasanovic L, Heller C, Mohr J, Bauer C, Riesch E, Becker A, Battke F, Hörtnagel K, Hornemann T, Suriyanarayanan S, Blankenburg M, Schulz JB, Claeys KG, Gess B, Katona I, Ferbert A, Vittore D, Grimm A, Wolking S, Schöls L, Lerche H, Korenke GC, Fischer D, Schrank B, Kotzaeridou U, Kurlemann G, Dräger B, Schirmacher A, Young P, Schlotter-Weigel B, Biskup S

Abstract
Hereditary neuropathies comprise a wide variety of chronic diseases associated to more than 80 genes identified to date. We herein examined 612 index patients with either a Charcot-Marie-Tooth phenotype, hereditary sensory neuropathy, familial amyloid neuropathy, or small fiber neuropathy using a customized multigene panel based on the next generation sequencing technique. In 121 cases (19.8%), we identified at least one putative pathogenic mutation. Of these, 54.4% showed an autosomal dominant, 33.9% an autosomal recessive, and 11.6% an X-linked inheritance. The most frequently affected genes were PMP22 (16.4%), GJB1 (10.7%), MPZ, and SH3TC2 (both 9.9%), and MFN2 (8.3%). We further detected likely or known pathogenic variants in HINT1, HSPB1, NEFL, PRX, IGHMBP2, NDRG1, TTR, EGR2, FIG4, GDAP1, LMNA, LRSAM1, POLG, TRPV4, AARS, BIC2, DHTKD1, FGD4, HK1, INF2, KIF5A, PDK3, REEP1, SBF1, SBF2, SCN9A, and SPTLC2 with a declining frequency. Thirty-four novel variants were considered likely pathogenic not having previously been described in association with any disorder in the literature. In one patient, two homozygous mutations in HK1 were detected in the multigene panel, but not by whole exome sequencing. A novel missense mutation in KIF5A was considered pathogenic because of the highly compatible phenotype. In one patient, the plasma sphingolipid profile could functionally prove the pathogenicity of a mutation in SPTLC2. One pathogenic mutation in MPZ was identified after being previously missed by Sanger sequencing. We conclude that panel based next generation sequencing is a useful, time- and cost-effective approach to assist clinicians in identifying the correct diagnosis and enable causative treatment considerations.

PMID: 28902413 [PubMed - indexed for MEDLINE]

Model Organisms Facilitate Rare Disease Diagnosis and Therapeutic Research.

Genetics. 2017 Sep;207(1):9-27

Authors: Wangler MF, Yamamoto S, Chao HT, Posey JE, Westerfield M, Postlethwait J, Members of the Undiagnosed Diseases Network (UDN), Hieter P, Boycott KM, Campeau PM, Bellen HJ

Abstract
Efforts to identify the genetic underpinnings of rare undiagnosed diseases increasingly involve the use of next-generation sequencing and comparative genomic hybridization methods. These efforts are limited by a lack of knowledge regarding gene function, and an inability to predict the impact of genetic variation on the encoded protein function. Diagnostic challenges posed by undiagnosed diseases have solutions in model organism research, which provides a wealth of detailed biological information. Model organism geneticists are by necessity experts in particular genes, gene families, specific organs, and biological functions. Here, we review the current state of research into undiagnosed diseases, highlighting large efforts in North America and internationally, including the Undiagnosed Diseases Network (UDN) (Supplemental Material, File S1) and UDN International (UDNI), the Centers for Mendelian Genomics (CMG), and the Canadian Rare Diseases Models and Mechanisms Network (RDMM). We discuss how merging human genetics with model organism research guides experimental studies to solve these medical mysteries, gain new insights into disease pathogenesis, and uncover new therapeutic strategies.

PMID: 28874452 [PubMed - indexed for MEDLINE]

Japan's initiative on rare and undiagnosed diseases (IRUD): towards an end to the diagnostic odyssey.

Eur J Hum Genet. 2017 Sep;25(9):1025-1028

Authors: Adachi T, Kawamura K, Furusawa Y, Nishizaki Y, Imanishi N, Umehara S, Izumi K, Suematsu M

Abstract
Japan has been facing challenges relating to specifically defined rare diseases, called Nan-Byo in Japanese (literally 'difficult'+'illness'), and has already taken measures for them since 1972. This governmental support has surely benefited Nan-Byo patients; however, those suffering from medically unidentified conditions do not fall into this scheme and thus still confront difficulty in obtaining an examination, a diagnosis, and a treatment. To identify such rare and often undiagnosed diseases, we must integrate systematic diagnosis by medical experts with phenotypic and genetic data matching. Thus, in collaboration with Nan-Byo researchers and the Japanese universal healthcare system, the Japan Agency for Medical Research and Development launched the Initiative on Rare and Undiagnosed Diseases (IRUD) in 2015. IRUD is an ambitious challenge to construct a comprehensive medical network and an internationally compatible data-sharing framework. Synergizing with existing next-generation sequencing capabilities and other infrastructure, the nationwide medical research consortium has successfully grown to accept more than 2000 undiagnosed registrants by December 2016. We also aim at expanding the concept of microattribution throughout the initiative; that is, proper credit as collaborators shall be given to local primary care physicians, nurses and paramedics, patients, their family members, and those supporting the affected individuals whenever appropriate. As it shares many challenges among similar global efforts, IRUD's future successes and lessons learned will significantly contribute to ongoing international endeavors, involving players in basic research, applied research, and societal implementation.

PMID: 28794428 [PubMed - indexed for MEDLINE]

How can we support the parents of children with a life-shortening disease?

Tidsskr Nor Laegeforen. 2017 Jun;137(11):810-812

Authors: Vatne TM

PMID: 28597637 [PubMed - indexed for MEDLINE]

Milrinone in congenital diaphragmatic hernia - a randomized pilot trial: study protocol, review of literature and survey of current practices.

Matern Health Neonatol Perinatol. 2017;3:27

Authors: Lakshminrusimha S, Keszler M, Kirpalani H, Van Meurs K, Chess P, Ambalavanan N, Yoder B, Fraga MV, Hedrick H, Lally KP, Nelin L, Cotten M, Klein J, Guilford S, Williams A, Chaudhary A, Gantz M, Gabrio J, Chowdhury D, Zaterka-Baxter K, Das A, Higgins RD

Abstract
Background: Congenital diaphragmatic hernia (CDH) is commonly associated with pulmonary hypoplasia and pulmonary hypertension (PH). PH associated with CDH (CDH-PH) is frequently resistant to conventional pulmonary vasodilator therapy including inhaled nitric oxide (iNO) possibly due to right and left ventricular dysfunction. Milrinone is an intravenous inotrope and lusitrope with pulmonary vasodilator properties and has been shown anecdotally to improve oxygenation in PH. We developed this pilot study to determine if milrinone infusion would improve oxygenation in neonates ≥36 weeks postmenstrual age (PMA) with CDH.
Methods/design: Data on pulmonary vasodilator management and outcome of CDH patients was collected from 18 university NICUs affiliated with the Neonatal Research Network (NRN) from 2011 to 2012. The proposed pilot will be a masked, placebo-controlled, multicenter, randomized trial of 66 infants with CDH with an oxygenation index (OI) ≥10 or oxygen saturation index (OSI) ≥5. The primary outcome is the oxygenation response, as determined by change in OI at 24 h after initiation of study drug. As secondary outcomes, we will determine oxygenation at 48 h and 72 h post-infusion, right ventricular pressures on echocardiogram and the incidence of systemic hypotension, arrhythmias, intracranial hemorrhage, survival without extracorporeal membrane oxygenation, and chronic lung disease (oxygen need at 28 days postnatal age). Finally, we will evaluate the pulmonary and nutritional status at 4, 8 and 12 months of age using a phone questionnaire.
Results: Three hundred thirty-seven infants with CDH were admitted to NRN NICUs in 2011 and 2012 of which 275 were ≥36 weeks PMA and were exposed to the following pulmonary vasodilators: iNO (39%), sildenafil (17%), milrinone (17%), inhaled epoprostenol (6%), intravenous epoprostenol (3%), and intravenous PGE1 (1%). ECMO was required in 36% of patients. Survival to discharge was 71%.
Discussion: CDH is an orphan disease with high mortality with few randomized trials evaluating postnatal management. Intravenous milrinone is a commonly used medication in neonatal/pediatric intensive care units and is currently used in 17% of patients with CDH within the NRN. This pilot study will provide data and enable further studies evaluating pulmonary vasodilator therapy in CDH.
Trial registration: ClinicalTrials.gov; NCT02951130; registered 14 October 2016.

PMID: 29209510 [PubMed]

The Epithelial Sodium Channel Is a Modifier of the Long-Term Nonprogressive Phenotype Associated with F508del CFTR Mutations.

Am J Respir Cell Mol Biol. 2017 Dec;57(6):711-720

Authors: Agrawal PB, Wang R, Li HL, Schmitz-Abe K, Simone-Roach C, Chen J, Shi J, Louie T, Sheng S, Towne MC, Brainson CF, Matthay MA, Kim CF, Bamshad M, Emond MJ, Gerard NP, Kleyman TR, Gerard C

Abstract
Cystic fibrosis (CF) remains the most lethal genetic disease in the Caucasian population. However, there is great variability in clinical phenotypes and survival times, even among patients harboring the same genotype. We identified five patients with CF and a homozygous F508del mutation in the CFTR gene who were in their fifth or sixth decade of life and had shown minimal changes in lung function over a longitudinal period of more than 20 years. Because of the rarity of this long-term nonprogressive phenotype, we hypothesized these individuals may carry rare genetic variants in modifier genes that ameliorate disease severity. Individuals at the extremes of survival time and lung-function trajectory underwent whole-exome sequencing, and the sequencing data were filtered to include rare missense, stopgain, indel, and splicing variants present with a mean allele frequency of <0.2% in general population databases. Epithelial sodium channel (ENaC) mutants were generated via site-directed mutagenesis and expressed for Xenopus oocyte assays. Four of the five individuals carried extremely rare or never reported variants in the SCNN1D and SCNN1B genes of the ENaC. Separately, an independently enriched rare variant in SCNN1D was identified in the Exome Variant Server database associated with a milder pulmonary disease phenotype. Functional analysis using Xenopus oocytes revealed that two of the three variants in δ-ENaC encoded by SCNN1D exhibited hypomorphic channel activity. Our data suggest a potential role for δ-ENaC in controlling sodium reabsorption in the airways, and advance the plausibility of ENaC as a therapeutic target in CF.

PMID: 28708422 [PubMed - indexed for MEDLINE]

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

"Rare Diseases"[Mesh] OR "orphan disease"

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

"Rare Diseases"[Mesh] OR "orphan disease"

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

"Rare Diseases"[Mesh] OR "orphan disease"

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

"Rare Diseases"[Mesh] OR "orphan disease"

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

"Rare Diseases"[Mesh] OR "orphan disease"

These pubmed results were generated on 2017/12/02

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

"Rare Diseases"[Mesh] OR "orphan disease"

These pubmed results were generated on 2017/12/01

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

"Rare Diseases"[Mesh] OR "orphan disease"

These pubmed results were generated on 2017/11/29

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

"Rare Diseases"[Mesh] OR "orphan disease"

These pubmed results were generated on 2017/11/29

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.

Treatment of pulmonary hypertension with left heart disease: a concise review.

Vasc Health Risk Manag. 2017;13:415-420

Authors: Desai A, Desouza SA

Abstract
Pulmonary hypertension (PH) is defined by a mean pulmonary artery pressure ≥ 25 mmHg, as determined by right heart catheterization. Pulmonary arterial hypertension (PAH) can no longer be considered an orphan disease given the increase in awareness and availability of new drugs. PH carries with it a dismal prognosis and leads to significant morbidity and mortality. Symptoms can range from dyspnea, fatigue and chest pain to right ventricular failure and death. PH is divided into five groups by the World Health Organization (WHO), based on etiology. The most common cause of PH in developed countries is left heart disease (group 2), owing to the epidemic of heart failure (HF). The data regarding prevalence, diagnosis and treatment of patients with group 2 PH is unclear as large, prospective, randomized controlled trials and standardized protocols do not exist. Current guidelines do not support the use of PAH-specific therapy in patients with group 2 PH. Prostacyclins, endothelin receptor antagonists, phosphodiesterase-5 inhibitors and guanylate cyclase stimulators have been tried in treatment of patients with HF and/or group 2 PH with mixed results. This review summarizes and critically appraises the evidence for diagnosis and treatment of patients with group 2 PH/HF and suggests directions for future research.

PMID: 29158679 [PubMed - in process]

A Multicenter, Retrospective Medical Record Review of X-Linked Myotubular Myopathy: The RECENSUS Study.

Muscle Nerve. 2017 Nov 17;:

Authors: Beggs AH, Byrne BJ, de Chastonay S, Haselkorn T, Hughes I, James ES, Kuntz NL, Simon J, Swanson LC, Yang ML, Yu ZF, Yum SW, Prasad S

Abstract
INTRODUCTION: X-linked myotubular myopathy (XLMTM), characterized by severe hypotonia, weakness, respiratory distress, and early mortality, is rare and natural history studies are few.
METHODS: RECENSUS is a multicenter chart review of male XLMTM patients characterizing disease burden and unmet medical needs. Data were collected between September 2014 and June 2016.
RESULTS: Analysis included 112 patients at six clinical sites. Most recent patient age recorded was ≤18 months for 40 patients and >18 months for 72 patients. Mean (SD) age at diagnosis was 3.7 (3.7) months and 54.3 (77.1) months, respectively. Mortality was 44% (64% ≤18 months; 32% >18 months). Premature delivery occurred in 34/110 (31%) births. Nearly all patients (90%) required respiratory support at birth. In the first year of life, patients underwent an average of 3.7 surgeries and spent 35% of the year in the hospital.
DISCUSSION: XLMTM is associated with high mortality, disease burden, and healthcare utilization. This article is protected by copyright. All rights reserved.

PMID: 29149770 [PubMed - as supplied by publisher]

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

"Rare Diseases"[Mesh] OR "orphan disease"

These pubmed results were generated on 2017/11/14

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

"Rare Diseases"[Mesh] OR "orphan disease"

These pubmed results were generated on 2017/11/14

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

"Rare Diseases"[Mesh] OR "orphan disease"

These pubmed results were generated on 2017/11/10

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.

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

"Rare Diseases"[Mesh] OR "orphan disease"

These pubmed results were generated on 2017/11/10

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.