title: Rapid-Onset Obesity with Hypothalamic Dysfunction, Hypoventilation, and Autonomic Dysregulation (ROHHAD): exome sequencing of trios, monozygotic twins and tumours.
abstract: BACKGROUND
  Rapid-onset Obesity with Hypothalamic Dysfunction, Hypoventilation, and Autonomic Dysregulation (ROHHAD) is thought to be a genetic disease caused by de novo mutations, though causative mutations have yet to be identified. We searched for de novo coding mutations among a carefully-diagnosed and clinically homogeneous cohort of 35 ROHHAD patients.
  
  
  METHODS
  We sequenced the exomes of seven ROHHAD trios, plus tumours from four of these patients and the unaffected monozygotic (MZ) twin of one (discovery cohort), to identify constitutional and somatic de novo sequence variants. We further analyzed this exome data to search for candidate genes under autosomal dominant and recessive models, and to identify structural variations. Candidate genes were tested by exome or Sanger sequencing in a replication cohort of 28 ROHHAD singletons.
  
  
  RESULTS
  The analysis of the trio-based exomes found 13 de novo variants. However, no two patients had de novo variants in the same gene, and additional patient exomes and mutation analysis in the replication cohort did not provide strong genetic evidence to implicate any of these sequence variants in ROHHAD. Somatic comparisons revealed no coding differences between any blood and tumour samples, or between the two discordant MZ twins. Neither autosomal dominant nor recessive analysis yielded candidate genes for ROHHAD, and we did not identify any potentially causative structural variations.
  
  
  CONCLUSIONS
  Clinical exome sequencing is highly unlikely to be a useful diagnostic test in patients with true ROHHAD. As ROHHAD has a high risk for fatality if not properly managed, it remains imperative to expand the search for non-exomic genetic risk factors, as well as to investigate other possible mechanisms of disease. In so doing, we will be able to confirm objectively the ROHHAD diagnosis and to contribute to our understanding of obesity, respiratory control, hypothalamic function, and autonomic regulation.
authors: Department of Medical Genetics, Cumming School of Medicine, Alberta Children's Hospital Research Institute, University of Calgary, Calgary, AB, Canada. sarah.barclay@ucalgary.ca.
authors: Sarah F
authors: SF
authors: Barclay
authors: Center for Autonomic Medicine in Pediatrics (CAMP) in Department of Pediatrics, Ann & Robert H. Lurie Children's Hospital of Chicago and Stanley Manne Children's Research Institute, Chicago, IL, USA. CRand@luriechildrens.org.
authors: Casey M
authors: CM
authors: Rand
authors: Department of Medical Genetics, Cumming School of Medicine, Alberta Children's Hospital Research Institute, University of Calgary, Calgary, AB, Canada. laborch@ucalgary.ca.
authors: Lauren A
authors: LA
authors: Borch
authors: Department of Medical Genetics, Cumming School of Medicine, Alberta Children's Hospital Research Institute, University of Calgary, Calgary, AB, Canada. lisnguye@ucalgary.ca.
authors: Lisa
authors: L
authors: Nguyen
authors: Department of Anatomy and Neurobiology, Washington University of Medicine, St Louis, MO, USA. pgray@pcg.wustl.edu.
authors: Paul A
authors: PA
authors: Gray
authors: Department of Medical Genetics, University of British Columbia and Child & Family Research Institute, Vancouver, B.C., Canada. wtgibson@cfri.ubc.ca.
authors: William T
authors: WT
authors: Gibson
authors: Department of Physiology and Pharmacology, Alberta Children's Hospital Research Institute and Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada. wilsonr@ucalgary.ca.
authors: Richard J A
authors: RJ
authors: Wilson
authors: Department of Medical Genetics, Cumming School of Medicine, Alberta Children's Hospital Research Institute, University of Calgary, Calgary, AB, Canada. gordonp@ucalgary.ca.
authors: Paul M K
authors: PM
authors: Gordon
authors: Department of Medical Genetics, Cumming School of Medicine, Alberta Children's Hospital Research Institute, University of Calgary, Calgary, AB, Canada. zed.aung@gmail.com.
authors: Zaw
authors: Z
authors: Aung
authors: Departments of Pediatrics, Neurological Sciences, and Biochemistry, Rush University Medical Center, Chicago, IL, USA. Elizabeth_Berry-Kravis@rush.edu.
authors: Elizabeth M
authors: EM
authors: Berry-Kravis
authors: Department of Pediatrics, Division of Pediatric Endocrinology, University of Illinois at Chicago, Chicago, IL, USA. diegoize@uic.edu.
authors: Diego
authors: D
authors: Ize-Ludlow
authors: Center for Autonomic Medicine in Pediatrics (CAMP) in Department of Pediatrics, Ann & Robert H. Lurie Children's Hospital of Chicago and Stanley Manne Children's Research Institute, Chicago, IL, USA. D-Weese-Mayer@Northwestern.edu.|Northwestern University Feinberg School of Medicine, Chicago, IL, USA. D-Weese-Mayer@Northwestern.edu.
authors: Debra E
authors: DE
authors: Weese-Mayer
authors: Department of Medical Genetics, Cumming School of Medicine, Alberta Children's Hospital Research Institute, University of Calgary, Calgary, AB, Canada. ntbech@ucalgary.ca.
authors: N Torben
authors: NT
authors: Bech-Hansen
mesh_terms: D001342:Autonomic Nervous System Diseases / Q000175:diagnosis / Q000235:genetics*; D002648:Child; D002675:Child, Preschool; D004252:DNA Mutational Analysis; D004200:Diseases in Twins / Q000235:genetics; D059472:Exome / Q000235:genetics*; D005260:Female; D018305:Ganglioneuroblastoma / Q000235:genetics*; D005729:Ganglioneuroma / Q000235:genetics*; D059014:High-Throughput Nucleotide Sequencing / Q000379:methods; D006801:Humans; D007027:Hypothalamic Diseases / Q000175:diagnosis / Q000235:genetics*; D007040:Hypoventilation / Q000175:diagnosis / Q000235:genetics*; D007223:Infant; D047908:Intracellular Signaling Peptides and Proteins / Q000235:genetics; D008297:Male; D009154:Mutation; D009363:Neoplasm Proteins / Q000235:genetics; D009765:Obesity / Q000175:diagnosis / Q000235:genetics*; D017346:Protein Serine-Threonine Kinases / Q000235:genetics; D017422:Sequence Analysis, DNA; D014430:Twins, Monozygotic / Q000235:genetics*
chemical_list: D047908:Intracellular Signaling Peptides and Proteins; D009363:Neoplasm Proteins; C111049:MAP-kinase-activated kinase 5; D017346:Protein Serine-Threonine Kinases