Prenatal Diagnosis
Prenatal Genetic Testing Services
Due to the time-sensitive nature of prenatal diagnosis, each sample receives case management by a genetic counselor. All tests requested for ongoing pregnancies are given the highest priority in the lab and are performed on a RUSH basis. Therefore, the turnaround time will be faster than for nonprenatal cases. Please contact a genetic counselor at 301-519-2100 or prenatal@genedx.com prior to sending a prenatal sample.
Cytogenetics and Biochemical Tests
GeneDx offers full-service molecular cytogenetic testing, including a custom-designed targeted prenatal array CGH test. The prenatal array will rule out 100 clinically defined genomic disorders as well as terminal, subtelomeric and pericentromeric chromosomal rearrangements. Supplementing these tests are: FISH that can be requested as a stand-alone test for genomic disorders or specific segmental aneuploidies, or as a follow-up test for parents of a proband with a positive array CGH result, chromosome analysis and amniotic fluid alpha-fetoprotein (AF-AFP) with reflex to acetylcholinesterase (AchE) if AF-AFP is elevated.
| Test Available | Fetal Indication | More Information |
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Advanced maternal age, Abnormal ultrasound findings, Suspected deletion/duplication syndrome, Family history of known or suspected chromosome imbalances |
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Advanced maternal age, Abnormal ultrasound findings, Abnormal maternal serum screen
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Prenatal Chromosomal Microarray(CMA): Targeted and Whole Genome
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Advanced maternal age, Abnormal ultrasound findings, Suspected deletion/duplication syndrome, Family history of known or suspected chromosome imbalances, Abnormal maternal serum screen |
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Amniotic Fluid Alpha-fetoprotein (AF-AFP) and Acetylcholinesterase (AChE)
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Abnormal ultrasound findings, including open neural tube defects and ventral wall defects, Abnormal maternal serum screening results |
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FISH analysis for Velocardiofacial Syndrome and DiGeorge Syndrome
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Abnormal ultrasound findings, especially conotruncal cardiac defects and/or cleft palate, Prenatal diagnosis in at-risk pregnancies, Family history of known or suspected VCFS, Confirmation of a clinical diagnosis |
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Multiple pregnancies |
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Whole Genome Chromosomal Microarray for Products of Conception (POC)
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Abnormal ultrasound findings, Ambiguous or normal chromosome analysis results, Suspected deletion/duplication syndrome, Miscarriage and Fetal demise |
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Abnormal Ultrasound Findings
GeneDx prenatal diagnostic services include full gene sequencing for a limited number of genetic disorders, a comprehensive prenatal Noonan syndrome panel as well as a custom-designed prenatal targeted array CGH. For more information for each test, see the printable information sheet below or under the Gene or Disorder on our menu of Diagnostic Tests.
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SRD5A2 gene, Full gene sequencing, Deletion/duplication testing is preformed if sequencing identifies a mutation in only one allele of the SRD5A2 gene
| Genetic Disorder | Fetal Ultrasound Indication | Test Available | More Information |
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Abnormal ultrasound findings, Ambiguous karyotype results, Suspected deletion/duplication syndrome, Family history of known or suspected chromosome imbalances |
Prenatal Targeted Chromosomal Microarray: 60K oligonucleotide array CGH with probes throughout the genome and within 100 common microdeletion/microduplication syndromes. Includes 18,000 SNP probes covering chromosomes known to contain imprinted genes. Prenatal Whole Genome Chromosomal Microarray: 180K oligonucleotide array CGH for detection of copy number variants anywhere in the unique sequence of the genome. Includes 66,000 SNP probes throughout the genome. |
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| Noonan syndrome |
Cystic hygroma, Increased nuchal translucency, Cardiac defects, Lymphedema, Macrosomia, Polyhydramnios |
Comprehensive Prenatal Noonan Syndrome Panel – GeneDx custom-designed resequencing array including all 8 genes currently known to cause Noonan syndrome or related disorders (BRAF, HRAS, KRAS, MAP2K1, MAP2K2, PTPN11, RAF1, and SOS1) and mutation specific analysis for the Ser2Gly SHOC2 gene mutation using bi-directional DNA sequencing. |
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| Holoprosencephaly |
Holoprosencephaly, Cleft lip/palate, Hydrocephalus |
TGIF, SHH, SIX3, and ZIC2 genes, Full gene sequencing , Deletion/duplication testing |
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| X-linked hydrocephalus / MASA syndrome / CRASH syndrome | Hydrocephalus and/or Aqueductal stenosis |
L1CAM gene (L1-cell adhesion molecule), Full gene sequencing, For female fetus only: Deletion/duplication testing |
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| Townes-Brocks syndrome | Fetal renal malformations accompanied by characteristic abnormalities of the limbs and extremities | SALL1 gene Full gene sequencing |
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| Duane-Radial-Ray syndrome / Acro-renal-ocular syndrome | Fetal renal malformations accompanied by characteristic abnormalities of the limbs and extremities |
SALL4 gene, Full gene sequencing, Deletion/duplication testing |
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| Holt-Oram syndrome | Characteristic upper-limb malformations and/or fetal heart defects |
TBX5 gene, Full gene sequencing |
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| CHARGE syndrome |
Fetal heart defects, CNS malformations, Cleft lip/palate, Renal and gastrointestinal abnormalities |
CHD7 gene, Full gene sequencing |
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| Ectrodactyly-Ectodermal Dysplasia-Cleft Lip/Palate (EEC) / Split Hand-Split Foot Malformation (SHFM) / Hay-Wells syndrome | Fetal limb and extremity abnormalities |
TP73L (TP63,p63) gene, Sequencing of select exons (hotspots) |
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| Smith-Lemli-Opitz syndrome |
Intrauterine growth retardation (IUGR), Major brain, heart, limb or renal malformations, Ambiguous genitalia with female genitalia or severe hypospadias seen in a XY fetus |
DHCR7 gene, Full gene sequencing, Deletion/duplication testing is performed if sequencing idenifies a mutation in only one allele of the DHCR7 gene **Prenatal measurement of 7-DHC levels is recommended prior to genetic testing** |
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| Androgen Insensitivity syndrome (AIS) |
Fetal karyotype is 46,XY but ultrasound reveals apparently female or ambiguous genitalia. |
AR gene, Full gene sequencing |
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| Campomelic dysplasia |
Fetal karyotype is 46,XY but ultrasound reveals apparently female or ambiguous genitalia, Limb shortening and/or bowing, Increased nuchal translucency and/or cystic hygroma |
SOX9 gene, Full gene sequencing, Deletion/duplication testing |
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| XY Complete or Partial Gonadal Dysgenesis |
Fetal karyotype is 46,XY but ultrasound reveals apparently female or ambiguous genitalia. |
SRY gene, Full gene sequencing |
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| Anophthalmia / Microphthalmia |
Abnormal inter- and/or intraorbital distance, Absence of globe(s) |
Full Gene Sequencing: SOX2, OTX2 and VSX2 genes, Deletion/duplication testing: SOX2 and OTX2 genes |
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| 5-Alpha Reductase Deficiency |
Fetal karyotype is 46,XY but ultrasound reveals apparently female or ambiguous genitalia. |
SRD5A2 gene, Full gene sequencing, Deletion/duplication testing is performed if sequencing identifies a mutation in only one allele of the SRD5A2 gene |
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| Zygosity |
Multiple pregnancies |
Zygosity Testing |
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| Miscarriage/Fetal Demise |
Abnormal ultrasound findings, Ambiguous chromosome analysis results, Suspected deletion/duplication syndrome, Miscarriage and Fetal demise |
Custom-designed 180K oligonucleotide array CGH for detection of copy number variants anywhere in the unique sequence of the genome. Includes targeted exon-level coverage of 75 genes associated with neurodevelopmental disorders and 66,000 SNP probes throughout the genome to detect stretches of homozygosity extending 10 Mb or longer. |
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GeneDx can provide prenatal diagnosis for known familial mutations, in any gene, for families that have had previous testing at GeneDx or elsewhere. For genes not on GeneDx’s standard menu, early preparation is critical. If all preliminary testing of controls or parents is complete, the turnaround time when testing known familial mutations is usually 2 weeks. Call 301-519-2100 or email prenatal@genedx.com to speak to a genetic counselor prior to sending a sample.
Prenatal Diagnosis for Known Familial Mutations includes:
- Case-management by a genetic counselor
- Duplicate analysis of fetal specimen
- Maternal cell contamination studies
- Comparison to positive familial controls (required)
- Usually 2-week turnaround if GeneDx has already tested key family members
Price and Turn-Around-Time: $2000; includes duplicate analysis, testing for maternal cell contamination, and internal control tests. Specimen requirements are 20 mg CVS, 20 mL AF if >15 weeks, 2 T25 flasks confluent cultured CV or AF. TAT is usually 2 weeks if parental controls have been successfully tested in advance.
If the proband was diagnosed at GeneDx, the next step is parental carrier testing. After that, subsequent prenatal diagnosis usually can be completed with a 2-week turnaround. If more than 6 months have elapsed since Carrier Testing, fresh parental specimens should accompany the fetal specimen for control purposes as needed in gene-specific and MCC tests.
If the proband was tested in another CLIA laboratory or a research laboratory, see the corresponding column below. If parents do not order Carrier Tests at GeneDx in advance, the 2-week TAT for prenatal diagnosis does not apply. If outside testing was done in a research laboratory, advance parental Carrier Tests are mandatory.
Choose one of the following links for specific step-by-step instructions
- Known Familial Mutations in
Autosomal Recessive Disorders - Known Familial Mutations in
Autosomal Dominant Disorders - Known Familial Mutations
in X-Linked Disorders
Known Familial Mutations in Autosomal Recessive Disorders
For recessive disorders, testing of both parents is an essential aspect of accurate prenatal diagnosis.
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Previous Testing Performed By
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GeneDx
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Other CLIA Laboratory
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Research Laboratory
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STEPS for Recessive Disorders
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1
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Submit the outside molecular lab results to GeneDx for review and pre-approval
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Not necessary
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Required
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Required
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2
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If possible provide DNA from the proband as a control*
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Not necessary
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Recommended*
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Strongly Recommended*
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3
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Order Parental carrier testing (#9011 or #9012 below) for each parent, ideally 1 month or more in advance.
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Strongly Recommended if not already done at GeneDx
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Strongly Recommended if not already done at GeneDx
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Required if not already done at GeneDx
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4
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Submit a fetal specimen for prenatal diagnosis (#902 below). Parental specimens must accompany the fetal specimen, if not sent within 6 months, even if parental carrier tests are not ordered.
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TAT will be 2 weeks in most cases
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TAT will be 2 weeks in most cases, if Step 3 is already complete
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TAT will be 2 weeks in most cases, if Step 3 is already complete
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Known Familial Mutations in Autosomal Dominant Disorders
For dominant disorders, testing of a positive control is an essential aspect of accurate prenatal diagnosis.
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Previous Testing Performed By
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GeneDx
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Other CLIA Laboratory
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Research Laboratory
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STEPS for Dominant Disorders
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1
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Submit the outside molecular lab results to GeneDx for review and pre-approval
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Not necessary
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Required
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Required
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2
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Order Mutation Confirmation (#9001 below) on a positive relative, 1 month or more in advance.
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Not necessary
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Optional; otherwise send as an internal control for Step 3 or 4; no separate report
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Required
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3
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If the parents elect carrier testing, order Carrier Testing (#9011 below). A positive control specimen is required, if not already sent
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Optional
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Optional
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Optional
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4
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Submit a fetal specimen for prenatal diagnosis (#902 below). Specimens that must accompany the fetal specimen if not sent within 6 months are Maternal (for MCC testing) and Positive Control.
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TAT will be 2 weeks in most cases
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TAT will be 2 weeks in most cases, if Step 2 already complete
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TAT will be 2 weeks in most cases, if Step 2 already complete
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Known Familial Mutations in X-Linked Disorders
For X-linked disorders, testing of a positive control is an essential aspect of accurate prenatal diagnosis.
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Previous Testing Performed By
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GeneDx
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Other CLIA Laboratory
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Research Laboratory
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STEPS for X-Linked Disorders
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1
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Submit the outside molecular lab results to GeneDx for review and pre-approval
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Not necessary
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Required
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Required
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2
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Order Mutation Confirmation (#9001 below) on a positive relative, 1 month or more in advance.
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Not necessary
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Optional; otherwise send as an internal control for Step 3 or 4; no separate report
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Required
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3
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If the mother elects carrier testing, order Carrier Testing (#9011 below). A positive control specimen is required, if not already sent.
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Optional
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Optional
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Optional
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4
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Submit a fetal specimen for prenatal diagnosis (#902 below). Specimens that must accompany the fetal specimen if not sent within 6 months are Maternal (for MCC testing) and Positive Control.
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TAT will be 2 weeks in most cases
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TAT will be 2 weeks in most cases, if Step 2 already complete
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TAT will be 2 weeks in most cases, if Step 2 already complete
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