Genetic Testing Company | The DNA Diagnostic Experts | GeneDx

Prenatal Diagnosis

Prenatal Genetic Testing Services

GeneDx provides prenatal genetic testing for known familial mutations, full gene sequencing for a limited number of genetic disorders, a comprehensive prenatal Noonan syndrome panel, prenatal cytogenetics and a custom-designed prenatal targeted array CGH.

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

Chromosome Analysis

Advanced maternal age, Abnormal ultrasound findings, Suspected deletion/duplication syndrome, Family history of known or suspected chromosome imbalances

 
 

Rapid Aneuploidy FISH

 

Advanced maternal age, Abnormal ultrasound findings, Abnormal maternal serum screen

 

 
 

Prenatal Chromosomal Microarray(CMA): Targeted and Whole Genome

 

Advanced maternal age, Abnormal ultrasound findings, Suspected deletion/duplication syndrome, Family history of known or suspected chromosome imbalances, Abnormal maternal serum screen

 
 
 
 
 

Amniotic Fluid Alpha-fetoprotein (AF-AFP) and Acetylcholinesterase (AChE)

 

Abnormal ultrasound findings, including open neural tube defects and ventral wall defects, Abnormal maternal serum screening results

 

FISH analysis for Velocardiofacial Syndrome and DiGeorge Syndrome

 

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

 
 

Zygosity Testing

 

Multiple pregnancies

 

Whole Genome Chromosomal Microarray for Products of Conception (POC)

 

Abnormal ultrasound findings, Ambiguous or normal chromosome analysis results, Suspected deletion/duplication syndrome, Miscarriage and Fetal demise

 
 

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.

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

Chromosomal or subchromosomal unbalanced abnormality, including known microdeletion or microduplication syndromes and uniparental disomy

 

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.

 
 
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.
 
Holoprosencephaly

Holoprosencephaly, Cleft lip/palate, Hydrocephalus

TGIF, SHH, SIX3, and ZIC2 genes, Full gene sequencing , Deletion/duplication testing

 
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

 
Townes-Brocks syndrome Fetal renal malformations accompanied by characteristic abnormalities of the limbs and extremities SALL1 gene Full gene sequencing
 
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

 
Holt-Oram syndrome Characteristic upper-limb malformations and/or fetal heart defects

TBX5 gene, Full gene sequencing

 
CHARGE syndrome

Fetal heart defects, CNS malformations, Cleft lip/palate, Renal and gastrointestinal abnormalities

CHD7 gene, Full gene sequencing

 
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)

 
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**

 
Androgen Insensitivity syndrome (AIS)

Fetal karyotype is 46,XY but ultrasound reveals apparently female or ambiguous genitalia.

AR gene, Full gene sequencing

 
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

 
XY Complete or Partial Gonadal Dysgenesis

Fetal karyotype is 46,XY but ultrasound reveals apparently female or ambiguous genitalia.

SRY gene, Full gene sequencing

 
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

 
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

 
Zygosity

Multiple pregnancies

Zygosity Testing

 
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.

 
Adrenal Hypoplasia Congenita (AHC), X-linked Male fetuses with low maternal uE3, particularly in the presence of a family history of adrenal insufficiency suggestive of X-linked AHC. NR0B1 gene, Full gene sequencing Test Info Sheet

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

For recessive disorders, testing of both parents is an essential aspect of accurate prenatal diagnosis. 

 
Previous Testing Performed By
GeneDx
Other CLIA Laboratory
Research Laboratory
STEPS for Recessive Disorders
1
Submit the outside molecular lab results to GeneDx for review and pre-approval
Not necessary
Required
Required
2
If possible provide DNA from the proband as a control*
Not necessary
Recommended*
Strongly Recommended*
3
Order Parental carrier testing (#9011 or #9012 below) for each parent, ideally 1 month or more in advance.
Strongly Recommended if not already done at GeneDx
Strongly Recommended if not already done at GeneDx
Required if not already done at GeneDx
4
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.
TAT will be 2 weeks in most cases
TAT will be 2 weeks in most cases, if Step 3 is already complete
TAT will be 2 weeks in most cases, if Step 3 is already complete

 

Prenatal Diagnosis for Known Familial Mutation

Known Familial Mutations in Autosomal Dominant Disorders

For dominant disorders, testing of a positive control is an essential aspect of accurate prenatal diagnosis. 

 
Previous Testing Performed By
GeneDx
Other CLIA Laboratory
Research Laboratory
STEPS for Dominant Disorders
1
Submit the outside molecular lab results to GeneDx for review and pre-approval
Not necessary
Required
Required
2
Order Mutation Confirmation (#9001 below) on a positive relative, 1 month or more in advance.
Not necessary
Optional; otherwise send as an internal control for Step 3 or 4; no separate report
Required
3
If the parents elect carrier testing, order Carrier Testing (#9011 below). A positive control specimen is required, if not already sent
Optional
Optional
Optional
4
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.
TAT will be 2 weeks in most cases
TAT will be 2 weeks in most cases, if Step 2 already complete
TAT will be 2 weeks in most cases, if Step 2 already complete

 

Prenatal Diagnosis for Known Familial Mutation

Known Familial Mutations in X-Linked Disorders

For X-linked disorders, testing of a positive control is an essential aspect of accurate prenatal diagnosis.

 
Previous Testing Performed By
GeneDx
Other CLIA Laboratory
Research Laboratory
STEPS for X-Linked Disorders
1
Submit the outside molecular lab results to GeneDx for review and pre-approval
Not necessary
Required
Required
2
Order Mutation Confirmation (#9001 below) on a positive relative, 1 month or more in advance.
Not necessary
Optional; otherwise send as an internal control for Step 3 or 4; no separate report
Required
3
If the mother elects carrier testing, order Carrier Testing (#9011 below). A positive control specimen is required, if not already sent.
Optional
Optional
Optional
4
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.
TAT will be 2 weeks in most cases
TAT will be 2 weeks in most cases, if Step 2 already complete
TAT will be 2 weeks in most cases, if Step 2 already complete

 

Prenatal Diagnosis for Known Familial Mutation

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