Hirschsprung Disease Panel

Summary
Is a 15 gene panel that includes assessment of non-coding variants.

Is ideal for patients with a clinical suspicion of Hirschsprung disease (HSCR).

Analysis methods
  • PLUS
Availability
4 weeks
Number of genes
15
Test code
MA1801
Panel tier
Tier 1
CPT Code *
81403, 81404 x2, 81405, 81406, 81407, 81479
* The CPT codes provided are based on AMA guidelines and are for informational purposes only. CPT coding is the sole responsibility of the billing party. Please direct any questions regarding coding to the payer being billed.

Summary

The Blueprint Genetics Hirschsprung Disease Panel (test code MA1801):

Read about our accreditations, certifications and CE-marked IVD medical devices here.

Some patients heterozygous for a *de* *novo* polyalanine repeat expansion mutations (PARMs) in the *PHOX2B* gene have isolated or more commonly syndromic Hirschsprung disease in association with with congenital central hypoventilation syndrome (CCHS, PMID 16888290). Repeat expansions are generally difficult to detect via NGS assays and their clinical validation at large scale is impossible due to lack of publicly available control samples with abnormal repeat expansions. So far, we have been able to detect and confirm stretches of 28 alanines instead of normal amount of 20 (genotype “20/28”). However, we do not know exact sensitivity or detection limit of our assay for these alanine repeats.

ICD Codes

Refer to the most current version of ICD-10-CM manual for a complete list of ICD-10 codes.

Sample Requirements

  • Blood (min. 1ml) in an EDTA tube
  • Extracted DNA, min. 2 μg in TE buffer or equivalent
  • Saliva (Please see Sample Requirements for accepted saliva kits)

Label the sample tube with your patient’s name, date of birth and the date of sample collection.

We do not accept DNA samples isolated from formalin-fixed paraffin-embedded (FFPE) tissue. In addition, if the patient is affected with a hematological malignancy, DNA extracted from a non-hematological source (e.g. skin fibroblasts) is strongly recommended.

Please note that, in rare cases, mitochondrial genome (mtDNA) variants may not be detectable in blood or saliva in which case DNA extracted from post-mitotic tissue such as skeletal muscle may be a better option.

Read more about our sample requirements here.

Hirschsprung disease (HSCR), or congenital intestinal aganglionosis, is a birth defect characterized by complete absence of neuronal ganglion cells from a portion of the intestinal tract. Nerve cells are critical to the functioning of the colon as they control the regular muscle contractions that keep food moving through the bowels. In HSCR the aganglionic segment includes the distal rectum and a variable length of contiguous proximal intestine. In 80% of individuals, aganglionosis is restricted to the rectosigmoid colon (short-segment disease), in 15%-20%, it extends proximal to the sigmoid colon (long-segment disease) and in about 5%, aganglionosis affects the entire large intestine (total colonic aganglionosis). Affected infants typically have impaired intestinal motility such as failure to pass meconium within the first 48 hours of life, constipation, emesis, abdominal pain or distention, and occasionally diarrhea in the first two months of life. However, in the milder forms the initial diagnosis of HSCR may be delayed until late childhood or adulthood, and therefore HSCR should be considered in anyone with lifelong severe constipation. Individuals with HSCR are at risk for enterocolitis and/or potentially lethal intestinal perforation. HSCR is considered a neurocristopathy, a disorder of cells and tissues derived from the neural crest, and may occur as an isolated finding or as part of a multisystem disorder. Both syndromic and nonsyndromic causes of HSCR are recognized. Roughly a third of children who have Hirschsprung’s disease have other organ system involvement. Examples of monogenic syndromic forms of HSCR (covered by this panel) are Waardenburg syndrome type 4 (autosomal recessive disease due to EDNRB, EDN3 mutations in which HSCR is common and autosomal dominant form with SOX10 mutations in which HSCR is present in almost 100% of cases), Mowat-Wilson syndrome (mutations in ZEB2, HSCR present in 41-71% of cases) and multiple endocrine neoplasia type 2 (MEN 2A and 2B) (mutations in RET). Approximately 50% of familial cases of HSCR are heterozygous for mutations in RET, however the penetrance of these mutations is only 50 to 70%, is gender-dependent, and varies according to the extent of aganglionosis. The incidence of HSCR is approximately 1/ 5,000 live births, but it varies among different populations.

Genes in the Hirschsprung Disease Panel and their clinical significance

To view complete table content, scroll horizontally.

Gene Associated phenotypes Inheritance ClinVar HGMD
BDNF Central hypoventilation syndrome, congenital AD 1 23
CELSR3 Hirschsprung disease AD 25
EDN3 Hirschsprung disease, Central hypoventilation syndrome, congenital, Waardenburg syndrome AD/AR 7 21
EDNRB Hirschsprung disease, ABCD syndrome, Waardenburg syndrome AD/AR 12 66
KIF1BP Goldberg-Shprintzen megacolon syndrome AR 7 10
L1CAM Mental retardation, aphasia, shuffling gait, and adducted thumbs (MASA) syndrome, Hydrocephalus due to congenital stenosis of aqueduct of Sylvius, Spastic, CRASH syndrome, Corpus callosum, partial agenesis XL 80 292
MITF Tietz albinism-deafness syndrome, Waardenburg syndrome, Coloboma, osteopetrosis, microphthalmia, macrocephaly, albinism, and deafness (COMMAD) AD/AR 32 58
NRG1 Nonsyndromic Hirschsprung disease AD/AR 1 10
NRTN Hirschsprung disease AD 2
PAX3 Craniofacial-deafness-hand syndrome, Waardenburg syndrome, type 1, Waardenburg syndrome, type 3 AD/AR 54 149
PHOX2B Central hypoventilation syndrome, congenital, Neuroblastoma, susceptiblity to, Neuroblastoma with Hirschsprung disease AD 11 86
RET Hirschsprung disease, Central hypoventilation syndrome, congenital, Pheochromocytoma, Medullary thyroid carcinoma, Multiple endocrine neoplasia AD 122 407
RMRP Cartilage-hair hypoplasia, Metaphyseal dysplasia without hypotrichosis, Anauxetic dysplasia AR 87 123
SOX10 Peripheral demyelinating neuropathy, central dysmyelination, Waardenburg syndrome, and Hirschsprung disease, Kallmann syndrome AD 56 148
ZEB2* Mowat-Wilson syndrome AD 154 287
#

The gene has suboptimal coverage (means <90% of the gene’s target nucleotides are covered at >20x with mapping quality score (MQ>20) reads), and/or the gene has exons listed under Test limitations section that are not included in the panel as they are not sufficiently covered with high quality sequence reads.

*

Some, or all, of the gene is duplicated in the genome. Read more.

The sensitivity to detect variants may be limited in genes marked with an asterisk (*) or number sign (#). Due to possible limitations these genes may not be available as single gene tests.

Gene refers to the HGNC approved gene symbol; Inheritance refers to inheritance patterns such as autosomal dominant (AD), autosomal recessive (AR), mitochondrial (mi), X-linked (XL), X-linked dominant (XLD) and X-linked recessive (XLR); ClinVar refers to the number of variants in the gene classified as pathogenic or likely pathogenic in this database (ClinVar); HGMD refers to the number of variants with possible disease association in the gene listed in Human Gene Mutation Database (HGMD). The list of associated, gene specific phenotypes are generated from CGD or Mitomap databases.

Non-coding variants covered by Hirschsprung Disease Panel

To view complete table content, scroll horizontally.

Gene Genomic location HG19 HGVS RefSeq RS-number
EDN3 Chr20:57875743 c.-125G>A NM_000114.2
EDN3 Chr20:57875849 c.-19C>A NM_000114.2 rs375594972
L1CAM ChrX:153128846 c.3531-12G>A NM_000425.4
L1CAM ChrX:153131293 c.2432-19A>C NM_000425.4
L1CAM ChrX:153133652 c.1704-75G>T NM_000425.4
L1CAM ChrX:153133926 c.1547-14delC NM_000425.4
L1CAM ChrX:153136500 c.523+12C>T NM_000425.4
PAX3 Chr2:223085913 c.958+28A>T NM_181459.3
RET Chr10:43572670 c.-37G>C NM_020975.4 rs751005619
RET Chr10:43572680 c.-27C>G NM_020975.4
RET Chr10:43582162 c.73+9385_73+9395delAGCAACTGCCA NM_020975.4 rs368137511
RET Chr10:43606948 c.1522+35C>T NM_020975.4 rs377130948
RET Chr10:43612192 c.2284+13C>T NM_020975.4
RET Chr10:43612198 c.2284+19C>T NM_020975.4
RET Chr10:43613947 c.2392+19T>C NM_020975.4 rs778745375
RMRP Chr9:35658026 NR_003051.3
RMRP Chr9:35658026 NR_003051.3
RMRP Chr9:35658026 NR_003051.3
RMRP Chr9:35658026 NR_003051.3 rs781730798
RMRP Chr9:35658027 NR_003051.3
RMRP Chr9:35658027 NR_003051.3
RMRP Chr9:35658027 NR_003051.3
RMRP Chr9:35658027 NR_003051.3 rs727502775
RMRP Chr9:35658027 NR_003051.3
RMRP Chr9:35658028 NR_003051.3
RMRP Chr9:35658028 NR_003051.3
RMRP Chr9:35658029 NR_003051.3
RMRP Chr9:35658029 NR_003051.3
RMRP Chr9:35658032 NR_003051.3
SOX10 Chr22:38379877 c.-84-2A>T NM_006941.3
SOX10 Chr22:38412215 c.-31954C>T NM_006941.3 rs606231342
SOX10 Chr22:38412781 c.-32520C>G NM_006941.3 rs533778281
ZEB2 Chr2:145274987 c.-69-1G>A NM_014795.3
ZEB2 Chr2:145274988 c.-69-2A>C NM_014795.3

Test Strengths

Some patients heterozygous for a *de* *novo* polyalanine repeat expansion mutations (PARMs) in the *PHOX2B* gene have isolated or more commonly syndromic Hirschsprung disease in association with with congenital central hypoventilation syndrome (CCHS, PMID 16888290). Repeat expansions are generally difficult to detect via NGS assays and their clinical validation at large scale is impossible due to lack of publicly available control samples with abnormal repeat expansions. So far, we have been able to detect and confirm stretches of 28 alanines instead of normal amount of 20 (genotype “20/28”). However, we do not know exact sensitivity or detection limit of our assay for these alanine repeats.

The strengths of this test include:

  • CAP accredited laboratory
  • CLIA-certified personnel performing clinical testing in a CLIA-certified laboratory
  • Powerful sequencing technologies, advanced target enrichment methods and precision bioinformatics pipelines ensure superior analytical performance
  • Careful construction of clinically effective and scientifically justified gene panels
  • Some of the panels include the whole mitochondrial genome (please see the Panel Content section)
  • Our Nucleus online portal providing transparent and easy access to quality and performance data at the patient level
  • ~2,000 non-coding disease causing variants in our clinical grade NGS assay for panels (please see ‘Non-coding disease causing variants covered by this panel’ in the Panel Content section)
  • Our rigorous variant classification scheme
  • Our systematic clinical interpretation workflow using proprietary software enabling accurate and traceable processing of NGS data
  • Our comprehensive clinical statements

Test Limitations

Genes with partial, or whole gene, segmental duplications in the human genome are marked with an asterisk (*) if they overlap with the UCSC pseudogene regions. The technology may have limited sensitivity to detect variants in genes marked with these symbols (please see the Panel content table above).

This test does not detect the following:

  • Complex inversions
  • Gene conversions
  • Balanced translocations
  • Some of the panels include the whole mitochondrial genome but not all (please see the Panel Content section)
  • Repeat expansion disorders unless specifically mentioned
  • Non-coding variants deeper than ±20 base pairs from exon-intron boundary unless otherwise indicated (please see above Panel Content / non-coding variants covered by the panel).

This test may not reliably detect the following:

  • Low level mosaicism in nuclear genes (variant with a minor allele fraction of 14.6% is detected with 90% probability)
  • Stretches of mononucleotide repeats
  • Low level heteroplasmy in mtDNA (>90% are detected at 5% level)
  • Indels larger than 50bp
  • Single exon deletions or duplications
  • Variants within pseudogene regions/duplicated segments
  • Some disease causing variants present in mtDNA are not detectable from blood, thus post-mitotic tissue such as skeletal muscle may be required for establishing molecular diagnosis.

The sensitivity of this test may be reduced if DNA is extracted by a laboratory other than Blueprint Genetics.

For additional information, please refer to the Test performance section.

The genes on the panel have been carefully selected based on scientific literature, mutation databases and our experience.

Our panels are sectioned from our high-quality, clinical grade NGS assay. Please see our sequencing and detection performance table for details regarding our ability to detect different types of alterations (Table).

Assays have been validated for various sample types including EDTA-blood, isolated DNA (excluding from formalin fixed paraffin embedded tissue), saliva and dry blood spots (filter cards). These sample types were selected in order to maximize the likelihood for high-quality DNA yield. The diagnostic yield varies depending on the assay used, referring healthcare professional, hospital and country. Plus analysis increases the likelihood of finding a genetic diagnosis for your patient, as large deletions and duplications cannot be detected using sequence analysis alone. Blueprint Genetics’ Plus Analysis is a combination of both sequencing and deletion/duplication (copy number variant (CNV)) analysis.

The performance metrics listed below are from an initial validation performed at our main laboratory in Finland. The performance metrics of our laboratory in Marlborough, MA, are equivalent.

Performance of Blueprint Genetics high-quality, clinical grade NGS sequencing assay for panels.

Sensitivity % (TP/(TP+FN) Specificity %
Single nucleotide variants 99.89% (99,153/99,266) >99.9999%
Insertions, deletions and indels by sequence analysis
1-10 bps 99.2% (7,745/7,806) >99.9999%
11-50 bps 99.13% (2,524/2,546) >99.9999%
Copy number variants (exon level dels/dups)
1 exon level deletion (heterozygous) 100% (20/20) NA
1 exon level deletion (homozygous) 100% (5/5) NA
1 exon level deletion (het or homo) 100% (25/25) NA
2-7 exon level deletion (het or homo) 100% (44/44) NA
1-9 exon level duplication (het or homo) 75% (6/8) NA
Simulated CNV detection
5 exons level deletion/duplication 98.7% 100.00%
Microdeletion/-duplication sdrs (large CNVs, n=37))
Size range (0.1-47 Mb) 100% (25/25)
     
The performance presented above reached by Blueprint Genetics high-quality, clinical grade NGS sequencing assay with the following coverage metrics
     
Mean sequencing depth 143X
Nucleotides with >20x sequencing coverage (%) 99.86%

Performance of Blueprint Genetics Mitochondrial Sequencing Assay.

Sensitivity % Specificity %
ANALYTIC VALIDATION (NA samples; n=4)
Single nucleotide variants
Heteroplasmic (45-100%) 100.0% (50/50) 100.0%
Heteroplasmic (35-45%) 100.0% (87/87) 100.0%
Heteroplasmic (25-35%) 100.0% (73/73) 100.0%
Heteroplasmic (15-25%) 100.0% (77/77) 100.0%
Heteroplasmic (10-15%) 100.0% (74/74) 100.0%
Heteroplasmic (5-10%) 100.0% (3/3) 100.0%
Heteroplasmic (<5%) 50.0% (2/4) 100.0%
CLINICAL VALIDATION (n=76 samples)
All types
Single nucleotide variants n=2026 SNVs
Heteroplasmic (45-100%) 100.0% (1940/1940) 100.0%
Heteroplasmic (35-45%) 100.0% (4/4) 100.0%
Heteroplasmic (25-35%) 100.0% (3/3) 100.0%
Heteroplasmic (15-25%) 100.0% (3/3) 100.0%
Heteroplasmic (10-15%) 100.0% (9/9) 100.0%
Heteroplasmic (5-10%) 92.3% (12/13) 99.98%
Heteroplasmic (<5%) 88.9% (48/54) 99.93%
Insertions and deletions by sequence analysis n=40 indels
Heteroplasmic (45-100%) 1-10bp 100.0% (32/32) 100.0%
Heteroplasmic (5-45%) 1-10bp 100.0% (3/3) 100.0%
Heteroplasmic (<5%) 1-10bp 100.0% (5/5) 99,997%
SIMULATION DATA /(mitomap mutations)
Insertions, and deletions 1-24 bps by sequence analysis; n=17
Homoplasmic (100%) 1-24bp 100.0% (17/17) 99.98%
Heteroplasmic (50%) 100.0% (17/17) 99.99%
Heteroplasmic (25%) 100.0% (17/17) 100.0%
Heteroplasmic (20%) 100.0% (17/17) 100.0%
Heteroplasmic (15%) 100.0% (17/17) 100.0%
Heteroplasmic (10%) 94.1% (16/17) 100.0%
Heteroplasmic (5%) 94.1% (16/17) 100.0%
Copy number variants (separate artifical mutations; n=1500)
Homoplasmic (100%) 500 bp, 1kb, 5 kb 100.0% 100.0%
Heteroplasmic (50%) 500 bp, 1kb, 5 kb 100.0% 100.0%
Heteroplasmic (30%) 500 bp, 1kb, 5 kb 100.0% 100.0%
Heteroplasmic (20%) 500 bp, 1kb, 5 kb 99.7% 100.0%
Heteroplasmic (10%) 500 bp, 1kb, 5 kb 99.0% 100.0%
The performance presented above reached by following coverage metrics at assay level (n=66)
Mean of medians Median of medians
Mean sequencing depth MQ0 (clinical) 18224X 17366X
Nucleotides with >1000x MQ0 sequencing coverage (%) (clinical) 100%
rho zero cell line (=no mtDNA), mean sequencing depth 12X

The target region for each gene includes coding exons and ±20 base pairs from the exon-intron boundary. In addition, the panel includes non-coding and regulatory variants if listed above (Non-coding variants covered by the panel). Some regions of the gene(s) may be removed from the panel if specifically mentioned in the ‘Test limitations” section above. If the test includes the mitochondrial genome the target region gene list contains the mitochondrial genes. 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. Our pipeline is streamlined to maximize sensitivity without sacrificing specificity. We have incorporated a number of reference population databases and mutation databases including, but not limited, to 1000 Genomes Project, gnomAD, ClinVar and HGMD into our clinical interpretation software to make the process effective and efficient. For missense variants, in silico variant prediction tools such as  SIFT, PolyPhen,MutationTaster are used to assist with variant classification. Through our online ordering and statement reporting system, Nucleus, ordering providers have access to the details of the analysis, including patient specific sequencing metrics, a gene level coverage plot and a list of regions with suboptimal coverage (<20X for nuclear genes and <1000X for mtDNA) if applicable. This reflects our mission to build fully transparent diagnostics where ordering providers can easily visualize the crucial details of the analysis process.

We provide customers with the most comprehensive clinical report available on the market. Clinical interpretation requires a fundamental understanding of clinical genetics and genetic principles. At Blueprint Genetics, our PhD molecular geneticists, medical geneticists, and clinical consultants prepare the clinical statement together by evaluating the identified variants in the context of the phenotypic information provided in the requisition form. Our goal is to provide clinically meaningful statements that are understandable for all medical professionals regardless of whether they have formal training in genetics.

Variant classification is the cornerstone of clinical interpretation and resulting patient management decisions. Our classifications follow the ACMG guideline 2015.

The final step in the analysis is orthogonal confirmation. Sequence and copy number variants classified as pathogenic, likely pathogenic, and variants of uncertain significance (VUS) are confirmed using bi-directional Sanger sequencing or by orthogonal methods such as qPCR/ddPCR when they do not meet our stringent NGS quality metrics for a true positive call.

Our clinical statement includes tables for sequencing and copy number variants that include basic variant information (genomic coordinates, HGVS nomenclature, zygosity, allele frequencies, in silico predictions, OMIM phenotypes, and classification of the variant). In addition, the statement includes detailed descriptions of the variant, gene, and phenotype(s) including the role of the specific gene in human disease, the mutation profile, information about the gene’s variation in population cohorts, and detailed information about related phenotypes. We also provide links to the references, abstracts, and variant databases used to help ordering providers further evaluate the reported findings if desired. The conclusion summarizes all of the existing information and provides our rationale for the classification of the variant.

Identification of pathogenic or likely pathogenic variants in dominant disorders or their combinations in different alleles in recessive disorders are considered molecular confirmation of the clinical diagnosis. In these cases, family member testing can be used for risk stratification. We do not recommend using variants of uncertain significance (VUS) for family member risk stratification or patient management. Genetic counseling is recommended.

Our interpretation team analyzes millions of variants from thousands of individuals with rare diseases. Our internal database and our understanding of variants and related phenotypes increases with every case analyzed. Our laboratory is therefore well-positioned to re-classify previously reported variants as new information becomes available. If a variant previously reported by Blueprint Genetics is re-classified, our laboratory will issue a follow-up statement to the original ordering healthcare provider at no additional cost, according to our latest follow-up reporting policy.