Hemophagocytic Lymphohistiocytosis Panel
Test code: HE1001
The Blueprint Genetics Hemophagocytic Lymphohistiocytosis Panel is a 13 gene test for genetic diagnostics of patients with clinical suspicion of Chediak-Higashi syndrome, familial hemophagocytic lymphohistiocytosis, Griscelli syndrome or lymphoproliferative syndrome.
Hemophagocytic lymphohistiocytosis (HLH) has been traditionally divided into familial (FHLH) and secondary HLH. Primary HLH is an autosomal recessive disease but syndromes that may manifest as HLH are caused by X-linked, autosomal dominant and autosomal recessive mutations. This panel is included in the Bone Marrow Failure Syndrome Panel and Comprehensive Hematology Panel.
About Hemophagocytic Lymphohistiocytosis
Hemophagocytic lymphohistiocytosis (HLH) is a macrophage-related disorder leading to uncontrolled proliferation of the cells of the mononuclear phagocyte system. The distinction between FHLH and secondary HLH may not be possible in the initial clinical setting until molecular diagnosis is available. Both forms usually have a triggering infectious agent. FHLH is potentially fatal disease with median survival time under two months after diagnosis if not treated properly. The treatment consists of immunosuppressive therapy and allogeneic stem cell transplantation. Mutations in the perforin gene (PRF1) account for 20-40% of all the cases with a defect in NK- and T cell cytotoxicity. Other genetic forms of FHLH include UNC13D, STXBP2 and STX11 genes. Mutations in many other genes causing variable syndromes associate with HLH such as MYO5A and RAB27Athat cause Griscelli syndrome types 1 and 2. Mutations in SH2D1A cause X-linked lymphoproliferative disease (XLP). Mutations in XIAP cause an X-linked form of familial HLH which is known as XLP2. Defects in LYST cause Chediak-Higashi syndrome. Defective MAGT1 cause immunodeficiency and increases the risk of Epstein Barr virus associated lymphoproliferation. Tumor necrosis factor receptor superfamily gene, FAS, cause autoimmune lymphopriliferative syndrome (ALPS). ITK encodes an intracellular tyrosine kinase in T-cells and it takes part in T-cell proliferation and differentiation. Mutations in RECQL4 cause Baller-Gerold syndrome, RAPADILINO syndrome and Rothmund-Thompson syndrome. Especially Rapadillino which is enriched in Finnish population may have a feature of NK cell deficiency leading to increased risk of HLH. The annual incidence of FHLH has been reported to be 1.2 per 1,000,000 in children (around 1:50,000 live born).
Results in 3-4 weeks. We do not offer a maternal cell contamination (MCC) test at the moment. We offer prenatal testing only for cases where the maternal cell contamination studies (MCC) are done by a local genetic laboratory. Read more: http://blueprintgenetics.com/faqs/#prenatal
|FAS||Autoimmune lymphoproliferative syndrome||AD/AR||22||136|
|MAGT1||Immunodeficiency, with magnesium defect, Epstein-Barr virus infection and neoplasia||XL||4||10|
|PRF1||Lymphoma, non-Hodgkin, Aplastic anemia, adult-onset, Hemophagocytic lymphohistiocytosis||AR||15||165|
|RAB27A||Griscelli syndrome, Elejalde syndrome||AR||10||45|
|RECQL4||Baller-Gerold syndrome, RAPADILINO syndrome, Rothmund-Thomson syndrome||AR||34||92|
|STX11||Hemophagocytic lymphohistiocytosis, familial||AR||5||15|
|STXBP2||Hemophagocytic lymphohistiocytosis, familial||AR||8||60|
|UNC13D||Hemophagocytic lymphohistiocytosis, familial||AR||9||139|
*Some regions of the gene are duplicated in the genome leading to limited sensitivity within the regions. Thus, low-quality variants are filtered out from the duplicated regions and only high-quality variants confirmed by other methods are reported out. Read more.
Gene, refers to HGNC approved gene symbol; Inheritance to inheritance patterns such as autosomal dominant (AD), autosomal recessive (AR) and X-linked (XL); ClinVar, refers to a number of variants in the gene classified as pathogenic or likely pathogenic in ClinVar (http://www.ncbi.nlm.nih.gov/clinvar/); HGMD, refers to a number of variants with possible disease association in the gene listed in Human Gene Mutation Database (HGMD, http://www.hgmd.cf.ac.uk/ac/). The list of associated (gene specific) phenotypes are generated from CDG (http://research.nhgri.nih.gov/CGD/) or Orphanet (http://www.orpha.net/) databases.
Blueprint Genetics offers a comprehensive Hemophagocytic Lymphohistiocytosis Panel that covers classical genes associated with Chediak-Higashi syndrome, familial hemophagocytic lymphohistiocytosis, Griscelli syndrome and lymphoproliferative syndrome. The genes are carefully selected based on the existing scientific evidence, our experience and most current mutation databases. Candidate genes are excluded from this first-line diagnostic test. The test does not recognise balanced translocations or complex inversions, and it may not detect low-level mosaicism. The test should not be used for analysis of sequence repeats or for diagnosis of disorders caused by mutations in the mitochondrial DNA.
Analytical validation is a continuous process at Blueprint Genetics. Our mission is to improve the quality of the sequencing process and each modification is followed by our standardized validation process. Average sensitivity and specificity in Blueprint NGS Panels is 99.3% and 99.9% for detecting SNPs. Sensitivity to for indels vary depending on the size of the alteration: 1-10bps (96.0%), 11-20 bps (88.4%) and 21-30 bps (66.7%). The longest detected indel was 46 bps by sequence analysis. Detection limit for Del/Dup (CNV) analysis varies through the genome depending on exon size, sequencing coverage and sequence content. The sensitivity is 71.5% for single exon deletions and duplications and 99% for three exons’ deletions and duplications. We have validated the assays for different starting materials including EDTA-blood, isolated DNA (no FFPE) and saliva that all provide high-quality results. The diagnostic yield varies substantially depending on the used assay, referring healthcare professional, hospital and country. Blueprint Genetics’ Plus Analysis (Seq+Del/Dup) maximizes the chance to find molecular genetic diagnosis for your patient although Sequence Analysis or Del/Dup Analysis may be cost-effective first line test if your patient’s phenotype is suggestive for a specific mutation profile.
The sequencing data generated in our laboratory is analyzed with our proprietary data analysis and annotation pipeline, integrating state-of-the art algorithms and industry-standard software solutions. Incorporation of rigorous quality control steps throughout the workflow of the pipeline ensures the consistency, validity and accuracy of results. The highest relevance in the reported variants is achieved through elimination of false positive findings based on variability data for thousands of publicly available human reference sequences and validation against our in-house curated mutation database as well as the most current and relevant human mutation databases. Reference databases currently used are the 1000 Genomes Project (http://www.1000genomes.org), the NHLBI GO Exome Sequencing Project (ESP; http://evs.gs.washington.edu/EVS), the Exome Aggregation Consortium (ExAC; http://exac.broadinstitute.org), ClinVar database of genotype-phenotype associations (http://www.ncbi.nlm.nih.gov/clinvar) and the Human Gene Mutation Database (http://www.hgmd.cf.ac.uk). The consequence of variants in coding and splice regions are estimated using the following in silico variant prediction tools: SIFT (http://sift.jcvi.org), Polyphen (http://genetics.bwh.harvard.edu/pph2/), and Mutation Taster (http://www.mutationtaster.org).
Through our online ordering and statement reporting system, Nucleus, the customer can access specific details of the analysis of the patient. This includes coverage and quality specifications and other relevant information on the analysis. This represents our mission to build fully transparent diagnostics where the customer gains easy access to crucial details of the analysis process.
In addition to our cutting-edge patented sequencing technology and proprietary bioinformatics pipeline, we also provide the customers with the best-informed clinical report on the market. Clinical interpretation requires fundamental clinical and genetic understanding. At Blueprint Genetics our geneticists and clinicians, who together evaluate the results from the sequence analysis pipeline in the context of phenotype information provided in the requisition form, prepare the clinical statement. Our goal is to provide clinically meaningful statements that are understandable for all medical professionals, even without training in genetics.
Variants reported in the statement are always classified using the Blueprint Genetics Variant Classification Scheme modified from the ACMG guidelines (Richards et al. 2015), which has been developed by evaluating existing literature, databases and with thousands of clinical cases analyzed in our laboratory. Variant classification forms the corner stone of clinical interpretation and following patient management decisions. Our statement also includes allele frequencies in reference populations and in silico predictions. We also provide PubMed IDs to the articles or submission numbers to public databases that have been used in the interpretation of the detected variants. In our conclusion, we summarize all the existing information and provide our rationale for the classification of the variant.
A final component of the analysis is the Sanger confirmation of the variants classified as likely pathogenic or pathogenic. This does not only bring confidence to the results obtained by our NGS solution but establishes the mutation specific test for family members. Sanger sequencing is also used occasionally with other variants reported in the statement. In the case of variant of uncertain significance (VUS) we do not recommend risk stratification based on the genetic finding. Furthermore, in the case VUS we do not recommend use of genetic information in patient management or genetic counseling. For some cases Blueprint Genetics offers a special free of charge service to investigate the role of identified VUS.
We constantly follow genetic literature adapting new relevant information and findings to our diagnostics. Relevant novel discoveries can be rapidly translated and adopted into our diagnostics without delay. These processes ensure that our diagnostic panels and clinical statements remain the most up-to-date on the market.
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ICD & CPT codes
Commonly used ICD-10 codes when ordering the Hemophagocytic Lymphohistiocytosis Panel
|D76.1||Familial hemophagocytic lymphohistiocytosis|
Accepted sample types
- EDTA blood, min. 1 ml
- Purified DNA, min. 5μg
- Saliva (Oragene DNA OG-500 kit)
Label the sample tube with your patient’s name, date of birth and the date of sample collection.
Note that we do not accept DNA samples isolated from formalin-fixed paraffin-embedded (FFPE) tissue.