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Test Code LAB1840 Differences in Sex Development Sequencing

Clinical System Name

Differences in Sex Development Seq (DSD Sequencing)

Description

Differences in sex development (DSD) are congenital conditions where there is a discrepancy between the chromosomal sex and the phenotypic (gonadal or genital) sex of an individual. There are nonsyndromic forms of DSD and syndromic forms, with syndromic forms of DSD distinguished by additional organ systems, growth, and/or cognitive development affected. This test is primarily designed to identify genetic causes of nonsyndromic forms of DSD.

  • DSD Sequencing Panel AKR1C2, AKR1C4, AMH, AMHR2, ANOS1, AR, CBX2, CDKN1C, CHD7, CUL7, CYP11A1, CYP17A1, CYP19A1, DHH, DHX37, DMRT1, DMRT2, FEZF1, FGF8, FGFR1, FSHB, GATA4, GNRH1, GNRHR, HESX1, HSD17B3, HSD3B2, IL17RD, KISS1R, LHCGR, LHX3, LHX4, MAMLD1, MAP3K1, MYRF, NR0B1, NR2F2, NR5A1, NSMF, PCSK1, POR, PROK2, PROKR2, PROP1, PSMC3IP, RSPO1, SEMA3A, SOX3, SOX9, SRD5A2, SRY, STAR, TAC3, TACR3, WDR11, WNT4, WT1, ZFPM2

 

  • Additional testing options - we offer the following additional options for custom DSD testing:
    • Single-gene sequencing When there is strong clinical suspicion, any gene listed on our DSD Sequencing Panel is available as a single-gene sequencing test.
    • Reflex to DSDSequencing Panel The option to reflex to the full DSD panel when the single-gene test is non-diagnostic.

 

Please contact LabGC@seattlechildrens.org if you would like to order reflexive testing after the original testing report has been issued.

Sample Requirements

Note: For patients who have had a whole blood transfusion, wait 10 days post transfusion to draw for genetic testing. No wait time is necessary for blood or saliva collection if the patient received leuko-reduced red cells or plasma.

 

Specimen: Whole blood

Container(s): Lavender/EDTA

Preferred Vol: 3 mL

Minimum Vol: 1 mL

Note: Heparin samples (Green tops) are unacceptable.

 

Specimen: Saliva collected using Oragene Dx OGD-575/675 collection kit.

Container: Oragene Dx OGD-575/675 collection kit

IMPORTANT NOTE: Manufacturer instructions must be followed. The Oragene Dx OGD575/675 kit is not for children under 6 months. Contact the lab directly for more information or to obtain a kit - 206-987-2617

 

Specimen: Extracted DNA from EDTA blood

Preferred: 5 mcg

Minimum: 2 mcg

Note: Isolation of nucleic acids for clinical testing must be performed in a CLIA-certified
laboratory or a laboratory meeting equivalent requirements as determined by the CAP
and/or the CMS. DNA concentration minimum 50 µg/mL; 260/280 ratio 1.70-2.00.

Processing Instructions

 

Specimen Type Description

Temperature

Storage instructions
Whole blood EDTA or ACD tube Refrigerate Molecular Genetics box in CPA refrigerator #2
Extracted DNA DNA aliquot tube Refrigerate Molecular Genetics box in CPA refrigerator #2
Saliva OGD-575/675 kit Room Temp Place in CPA Cytogenetics room temp box with requisition

Off-site collection: Refrigerate blood samples until ready to ship.  Transport blood, saliva, or DNA at room temperature via overnight shipping.

Stability

Stability

Specimen Type Temperature Time
Whole blood, extracted DNA RT 3-5 d
Whole blood, extracted DNA 2 - 8 C

7 d

Saliva, extracted from ORAgene Dx OGD-575/675

Room temperature or refrigerated up to 2 weeks
Extracted DNA -20 C or -70 C  years

Note: Whole blood samples > 7days may be submitted to be assessed by our lab for acceptability for testing.

Availability

STAT Performed TAT
Contact lab Monday - Friday 4-6 weeks

Performing Laboratory

Seattle Children's Laboratory

Department

Department:  Molecular Genetics Laboratory

Phone: 206-987-3872

Lab Client Services: 206-987-2617

Lab Genetic Counselor: LabGC@seattlechildrens.org

CPT Codes

81479

Methodology

Method: Next Generation Sequencing technology using an Illumina NextSeq instrument. Target region includes coding exons and a minimum of 10 bp of flanking intron boundaries of the genes tested. Target enrichment performed using a custom Integrated DNA Technologies (IDT) Exome Hyb Panel v2. 

 

Average coverage ~150x, depth of coverage for all target regions is at least 20x except exon 8 of the AKR1C2 gene (NM_001393392.1).

 

Reported gene set: AKR1C2, AKR1C4, AMH, AMHR2, ANOS1, AR, CBX2, CDKN1C, CHD7, CUL7, CYP11A1, CYP17A1, CYP19A1, DHH, DHX37, DMRT1, DMRT2, FEZF1, FGF8, FGFR1, FSHB, GATA4, GNRH1, GNRHR, HESX1, HSD17B3, HSD3B2, IL17RD, KISS1R, LHCGR, LHX3, LHX4, MAMLD1, MAP3K1, MYRF, NR0B1, NR2F2, NR5A1, NSMF, PCSK1, POR, PROK2, PROKR2, PROP1, PSMC3IP, RSPO1, SEMA3A, SOX3, SOX9, SRD5A2, SRY, STAR, TAC3, TACR3, WDR11, WNT4, WT1, ZFPM2

 

Limitations:

This testing is performed on an exome backbone with analysis restricted to the panel genes. This method can detect single nucleotide variants (SNVs), small deletions, small insertions, and copy number variants in the regions targeted. Some regions cannot be efficiently captured due to sequence homology or sequence properties. This method will not detect large insertions and deletions, complex indels, structural variants (e.g. inversions, translocations), short tandem repeats, or other complex variants. Variants located outside of targeted regions will not be detected.

 

Based on validation studies, the bioinformatics pipeline showed precision and detection >99% for SNVs in regions with coverage greater than 20x and high mapping quality. Sensitivity for CNVs involving multiple genes is >99% and sensitivity for intragenic CNVs is >90%. Mosaic sequence variants present at <25% allele frequency may not be reliably detected, and detection sensitivity is dependent on the nature of the variant. The sensitivity of detection of mosaic copy number variants has not been evaluated.

Reference Range

Interpretive report will be provided. Variants are not reported if they are considered benign.

Clinical Utility

Approximately 40% of individuals with a DSD will have an underlying genetic etiology identified by our DSD Sequencing Panel. Timely identification of the genetic cause of a DSD can direct clinical management.

 

The most commonly involved genes in DSD include SRY, NR5A1, MAP3K1, DHH, NR0B1 (DAX1), WNT4, CYP21A2, and SOX9. CYP21A2 is not included in this panel due to pseudogene complexity.

Requisition

Molecular Genetics