title: Targeted high-throughput sequencing for genetic diagnostics of hemophagocytic lymphohistiocytosis.
abstract: BACKGROUND
  Hemophagocytic lymphohistiocytosis (HLH) is a rapid-onset, potentially fatal hyperinflammatory syndrome. A prompt molecular diagnosis is crucial for appropriate clinical management. Here, we validated and prospectively evaluated a targeted high-throughput sequencing approach for HLH diagnostics.
  
  
  METHODS
  A high-throughput sequencing strategy of 12 genes linked to HLH was validated in 13 patients with previously identified HLH-associated mutations and prospectively evaluated in 58 HLH patients. Moreover, 2504 healthy individuals from the 1000 Genomes project were analyzed in silico for variants in the same genes.
  
  
  RESULTS
  Analyses revealed a mutation detection sensitivity of 97.3%, an average coverage per gene of 98.0%, and adequate coverage over 98.6% of sites previously reported as mutated in these genes. In the prospective cohort, we achieved a diagnosis in 22 out of 58 patients (38%). Genetically undiagnosed HLH patients had a later age at onset and manifested higher frequencies of known secondary HLH triggers. Rare, putatively pathogenic monoallelic variants were identified in nine patients. However, such monoallelic variants were not enriched compared with healthy individuals.
  
  
  CONCLUSIONS
  We have established a comprehensive high-throughput platform for genetic screening of patients with HLH. Almost all cases with reduced natural killer cell function received a diagnosis, but the majority of the prospective cases remain genetically unexplained, highlighting genetic heterogeneity and environmental impact within HLH. Moreover, in silico analyses of the genetic variation affecting HLH-related genes in the general population suggest caution with respect to interpreting causality between monoallelic mutations and HLH. A complete understanding of the genetic susceptibility to HLH thus requires further in-depth investigations, including genome sequencing and detailed immunological characterization.
authors.affiliation: Childhood Cancer Research Unit, Department of Women's and Children's Health, Karolinska Institutet, Karolinska University Hospital Solna, SE-17176, Stockholm, Sweden. Bianca.Tesi@ki.se.|Clinical Genetics Unit, Department of Molecular Medicine and Surgery, and Center for Molecular Medicine, Karolinska Institutet, Karolinska University Hospital, Stockholm, Sweden. Bianca.Tesi@ki.se.
authors.forename: Bianca
authors.initials: B
authors.lastname: Tesi
authors.affiliation: Clinical Genetics Unit, Department of Molecular Medicine and Surgery, and Center for Molecular Medicine, Karolinska Institutet, Karolinska University Hospital, Stockholm, Sweden.|Clinical Genetics, Karolinska University Hospital, Stockholm, Sweden.
authors.forename: Kristina
authors.initials: K
authors.lastname: Lagerstedt-Robinson
authors.affiliation: Centre for Infectious Medicine, Department of Medicine, Karolinska Institutet, Karolinska University Hospital Huddinge, SE-14186, Stockholm, Sweden.
authors.forename: Samuel C C
authors.initials: SC
authors.lastname: Chiang
authors.affiliation: Childhood Cancer Research Unit, Department of Women's and Children's Health, Karolinska Institutet, Karolinska University Hospital Solna, SE-17176, Stockholm, Sweden.|Clinical Genetics Unit, Department of Molecular Medicine and Surgery, and Center for Molecular Medicine, Karolinska Institutet, Karolinska University Hospital, Stockholm, Sweden.
authors.forename: Eya
authors.initials: E
authors.lastname: Ben Bdira
authors.affiliation: Department of Pediatrics and Adolescent Medicine, American University of Beirut, Beirut, Lebanon.
authors.forename: Miguel
authors.initials: M
authors.lastname: Abboud
authors.affiliation: Department of Pediatric Hematology, Izmir Katip Celebi University Medical Faculty, Tepecik Training and Research Hospital, Izmir, Turkey.
authors.forename: Burcu
authors.initials: B
authors.lastname: Belen
authors.affiliation: Department of Pediatric Hematology Oncology, Istanbul Medical School, Istanbul, Turkey.
authors.forename: Omer
authors.initials: O
authors.lastname: Devecioglu
authors.affiliation: Department of Oncology and Pediatrics, Aga Khan University, Karachi, Pakistan.
authors.forename: Zehra
authors.initials: Z
authors.lastname: Fadoo
authors.affiliation: Viva-University Children's Cancer Centre, Department of Paediatric, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore.
authors.forename: Allen E J
authors.initials: AE
authors.lastname: Yeoh
authors.affiliation: Department of Pediatrics, Oslo University Hospital, Oslo, Norway.
authors.forename: Hans Christian
authors.initials: HC
authors.lastname: Erichsen
authors.affiliation: Department of Pediatrics and Adolescence, PEDEGO Research Unit, Oulu University Hospital, Oulu, Finland.
authors.forename: Merja
authors.initials: M
authors.lastname: Möttönen
authors.affiliation: Department of Pediatric Immunology, Erciyes University Medical Faculty, Kayseri, Turkey.
authors.forename: Himmet Haluk
authors.initials: HH
authors.lastname: Akar
authors.affiliation: Department of Perioperative and Intensive Care, Children's Hospital, Helsinki University Central Hospital, Helsinki, Finland.
authors.forename: Johanna
authors.initials: J
authors.lastname: Hästbacka
authors.affiliation: Pediatric Hematology Unit of the Department of Pediatrics, Medical School of Gazi University, Ankara, Turkey.
authors.forename: Zuhre
authors.initials: Z
authors.lastname: Kaya
authors.affiliation: Hematology-Oncology Unit, Department of Pediatrics, São João Hospital Center, Oporto, Portugal.
authors.forename: Susana
authors.initials: S
authors.lastname: Nunes
authors.affiliation: Department of Pediatric Immunology, Erciyes University Medical Faculty, Kayseri, Turkey.
authors.forename: Turkan
authors.initials: T
authors.lastname: Patiroglu
authors.affiliation: Institute of Clinical Sciences, Department of Pediatrics, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden.|Queen Silvia Children's Hospital, Gothenburg, Sweden.
authors.forename: Magnus
authors.initials: M
authors.lastname: Sabel
authors.affiliation: Department of Pediatric Hematology and Oncology and Bone Marrow Transplantation Unit, Medipol School of Medicine, Medipol University, Istanbul, Turkey.
authors.forename: Ebru Tugrul
authors.initials: ET
authors.lastname: Saribeyoglu
authors.affiliation: Department of Medicine, Haukeland University Hospital, Bergen, Norway.
authors.forename: Tor Henrik
authors.initials: TH
authors.lastname: Tvedt
authors.affiliation: Department of Pediatrics, Division of Pediatric Hematology and Oncology, Faculty of Medicine, Erciyes University, Kayseri, Turkey.
authors.forename: Ekrem
authors.initials: E
authors.lastname: Unal
authors.affiliation: Department of Pediatrics, Division of Pediatric Hematology, Ankara, Turkey.
authors.forename: Sule
authors.initials: S
authors.lastname: Unal
authors.affiliation: Division of Pediatric Hematology and Oncology, Istanbul School of Medicine, Istanbul University, Istanbul, Turkey.
authors.forename: Aysegul
authors.initials: A
authors.lastname: Unuvar
authors.affiliation: Childhood Cancer Research Unit, Department of Women's and Children's Health, Karolinska Institutet, Karolinska University Hospital Solna, SE-17176, Stockholm, Sweden.|Clinical Genetics Unit, Department of Molecular Medicine and Surgery, and Center for Molecular Medicine, Karolinska Institutet, Karolinska University Hospital, Stockholm, Sweden.
authors.forename: Marie
authors.initials: M
authors.lastname: Meeths
authors.affiliation: Childhood Cancer Research Unit, Department of Women's and Children's Health, Karolinska Institutet, Karolinska University Hospital Solna, SE-17176, Stockholm, Sweden.
authors.forename: Jan-Inge
authors.initials: JI
authors.lastname: Henter
authors.affiliation: Clinical Genetics Unit, Department of Molecular Medicine and Surgery, and Center for Molecular Medicine, Karolinska Institutet, Karolinska University Hospital, Stockholm, Sweden.|Clinical Genetics, Karolinska University Hospital, Stockholm, Sweden.
authors.forename: Magnus
authors.initials: M
authors.lastname: Nordenskjöld
authors.affiliation: Centre for Infectious Medicine, Department of Medicine, Karolinska Institutet, Karolinska University Hospital Huddinge, SE-14186, Stockholm, Sweden. Yenan.Bryceson@ki.se.|Broegelmann Research Laboratory, The Gades Institute, University of Bergen, Bergen, Norway. Yenan.Bryceson@ki.se.
authors.forename: Yenan T
authors.initials: YT
authors.lastname: Bryceson
mesh_terms: D000293:Adolescent; D000328:Adult; D017668:Age of Onset; D000368:Aged; D001483:Base Sequence; D002648:Child; D002675:Child, Preschool; D015331:Cohort Studies; D005260:Female; D020022:Genetic Predisposition to Disease; D005820:Genetic Testing; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D051359:Lymphohistiocytosis, Hemophagocytic / Q000175:diagnosis* / Q000235:genetics*; D008297:Male; D008875:Middle Aged; D009154:Mutation; D011446:Prospective Studies; D017422:Sequence Analysis, DNA; D055815:Young Adult