Septo-Optic Dysplasia Panel

Summary
  • Is a 4 gene panel that includes assessment of non-coding variants
  • Is ideal for patients with a clinical suspicion of septo-optic dysplasia.

Analysis methods
  • PLUS
Availability

4 weeks

Number of genes

4

Test code

MA2201

Panel size

Small

CPT codes
81479

Summary

The Blueprint Genetics Septo-Optic Dysplasia Panel (test code MA2201):

ICD codes

Commonly used ICD-10 code(s) when ordering the Septo-Optic Dysplasia Panel

ICD-10 Disease
Q04.8 Septo-optic dysplasia (SOD)

Sample Requirements

  • Blood (min. 1ml) in an EDTA tube
  • Extracted DNA, min. 2 μg in TE buffer or equivalent
  • Saliva (Oragene DNA OG-500 kit/OGD-500 or OG-575 & OGD-575)

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. Read more about our sample requirements here.

Septo-optic dysplasia (SOD) is a clinically heterogeneous disorder characterized by the classical triad of optic nerve hypoplasia, pituitary hormone abnormalities and midline brain defects. Severity varies and only 30% of patients manifest the complete clinical triad. Some patients have SOD associated with multiple congenital anomalies at birth, whereas others may have growth failure and/or visual anomalies during childhood. Significant visual impairment occurs in 23% of patients and the optic nerve hypoplasia can be uni- or bilateral (57% and 32% of cases, respectively). Growth hormone deficiency, leading to short stature in childhood, is the most frequent endocrine anomaly and hypopituitarism is present in 62-80% of patients. Other hormone insufficiencies may also develop. Additional features can include midline brain defects, cortical malformations, intellectual deficit and neurological manifestations. The incidence is estimated at 1/10,000 live births. The majority of SOD cases are sporadic but familial cases have been described. Both homozygous (autosomal recessive transmission) and heterozygous (autosomal dominant transmission) HESX1 mutations have been described in familial cases. SOX2 mutations are also associated with anophthalmia/microphthalmia and features of SOD, and OTX2 mutations are associated with hypopituitarism and anterior pituitary hypoplasia, with or without eye defects. The differential diagnosis includes congenital hypopituitarism and holoprosencephaly.

Genes in the Septo-Optic Dysplasia Panel and their clinical significance

Gene Associated phenotypes Inheritance ClinVar HGMD
HESX1 Septooptic dysplasia, Pituitary hormone deficiency, combined AR/AD 15 26
OTX2 Microphthalmia, syndromic, Pituitary hormone deficiency, combined, Retinal dystrophy, early-onset, and pituitary dysfunction AD 23 73
PAX6 Aniridia, cerebellar ataxia, and mental retardation (Gillespie syndrome), Keratitis, Coloboma, ocular, Cataract with late-onset corneal dystrophy, Morning glory disc anomaly, Foveal hypoplasia, Aniridia, Optic nerve hypoplasia, Peters anomaly AD 144 550
SOX2* Microphthalmia, syndromic AD 34 104

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

# 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.

The sensitivity to detect variants may be limited in genes marked with an asterisk (*) or number sign (#)

Gene refers to the HGNC approved gene symbol; Inheritance refers to inheritance patterns such as autosomal dominant (AD), autosomal recessive (AR), 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 Orphanet databases.

Non-coding variants covered by Septo-Optic Dysplasia Panel

Gene Genomic location HG19 HGVS RefSeq RS-number
PAX6 Chr11:31685945 c.*125537G>T NM_000280.4 rs606231388
PAX6 Chr11:31812434 c.1033-42_1033-26delATGTGTTCCTCAGTAACinsG NM_000280.4
PAX6 Chr11:31816377 c.524-41T>G NM_000280.4
PAX6 Chr11:31823338 c.142-14C>G NM_000280.4 rs1131692291
PAX6 Chr11:31828391 c.-52+5delG NM_000280.4
PAX6 Chr11:31828391 c.-52+3_-52+6delAAGTinsTG NM_000280.4
PAX6 Chr11:31828392 c.-52+3_-52+4delAA NM_000280.4
PAX6 Chr11:31828395 c.-52+1delG NM_000280.4
PAX6 Chr11:31828396 c.-52+1G>A NM_000280.4
PAX6 Chr11:31828456 c.-115_-112delACTA NM_000280.4 rs1011844558
PAX6 Chr11:31828461 c.-118_-117delTT NM_000280.4
PAX6 Chr11:31828469 c.-125dupG NM_000280.4
PAX6 Chr11:31828474 c.-128-1G>T NM_000280.4
PAX6 Chr11:31828474 c.-128-2delA NM_000280.4 rs1131692282
PAX6 Chr11:31832372 c.-138_-129+3delCCTCATAAAGGTG NM_000280.4
PAX6 Chr11:31832374 c.-129+2T>A NM_000280.4
PAX6 Chr11:31832375 c.-129+1G>A NM_000280.4

Added and removed genes from the panel

Genes added Genes removed


Test Strengths

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
  • Our Nucleus online portal providing transparent and easy access to quality and performance data at the patient level
  • Our publicly available analytic validation demonstrating complete details of test performance
  • ~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
  • Mitochondrial DNA variants
  • 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 (variant with a minor allele fraction of 14.6% is detected with 90% probability)
  • Stretches of mononucleotide repeats
  • Indels larger than 50bp
  • Single exon deletions or duplications
  • Variants within pseudogene regions/duplicated segments

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 and see our Analytic Validation.

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.

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%
     
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%

Bioinformatics

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. 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 <20X sequencing depth if applicable. This reflects our mission to build fully transparent diagnostics where ordering providers can easily visualize the crucial details of the analysis process.

Clinical interpretation

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 corner stone of clinical interpretation and resulting patient management decisions. Our classifications follow the Blueprint Genetics Variant Classification Schemes based on the ACMG guideline 2015. Minor modifications were made to increase reproducibility of the variant classification and improve the clinical validity of the report. Our experience with tens of thousands of clinical cases analyzed at our laboratory allowed us to further develop the industry standard.

The final step in the analysis is orthogonal confirmation. Sequence variants classified as pathogenic, likely pathogenic and variants of uncertain significance (VUS) are confirmed using bi-directional Sanger sequencing when they do not meet our stringent NGS quality metrics for a true positive call.
Reported heterozygous and homo/hemizygous copy number variations with a size <10 and <3 target exons are confirmed by orthogonal methods such as qPCR if the specific CNV has been seen and confirmed less than three times at Blueprint Genetics.

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 health care provider at no additional cost.

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