60K Oligonucleotide + SNP Prenatal Array CGH
Comparative Genomic Hybridization
Genetics Center is pleased to offer the latest in array-based comparative genomic hybridization (CGH). testing in a prenatal setting. Array CGH is a technology with the ability to detect chromosome imbalances beyond that of more conventional techniques. Our high-resolution targeted prenatal array (GCPrenatal Array) containing a combination of 60,000 oligonucleotide and SNP probes, is designed to cover 312 specific regions known to be associated with childhood-onset disorders. This includes detection of loss of heterozygosity for six clinically relevant chromosomes, including chromosomes 7, 11, 14, 15, 16 and 20,which may indicate uniparental disomy (UPD). As there are many abnormal phenotypes that are associated with chromosomal imbalances (subtle gains or losses of genetic material), the identification of specific abnormalities (or copy number variants) is helpful in the prenatal setting for accurate diagnosis and medical management.
Reasons for Testing
Prenatal Abnormalities
The American College of Obstetricians and Gynecologists (ACOG) Committee Opinion Number 446 recommends that array CGH be offered as an adjunct tool in prenatal cases with abnormal anatomical findings on ultrasound and a normal conventional karyotype.
Prenatal array CGH can also be offered to patients requesting more detailed chromosome analysis or when clarification of an abnormal karyotype is necessary. Conventional karyotype and maternal cell contamination (MCC) studies are concurrently performed for all prenatal array CGH testing.
Products of Conception (POC)
Array CGH can be performed to detect copy number variants in the fetal genome that may explain a fetal demise. Maternal cell contamination (MCC) studies are performed for POC prenatal targeted array CGH testing.
Prenatal Array Testing Methods
A microarray is a slide with thousands of DNA probes that are specific to regions of our chromosomes. The probes in the array are specifically selected to evenly cover the entire genome as well as look at specific regions that are known to be associated with human disease. This targeted prenatal array is a combined platform of both oligonucleotide and SNP probes.
Abnormalities Detected by GCPrenatal Array include:
- Well-known microdeletion and microduplication syndromes, such as Williams syndrome, 22q11.2 deletion syndrome, Prader-Willi syndrome, Angelman syndrome, and many others.
- Loss of Heterozygosity for chromosomes 7, 11, 14, 15, 16 and 20, which could indicate uniparental disomy (UPD).
- Chromosomal aneuploidies, such as Down syndrome, trisomy 18, and many others.
- Gains or losses at the ends of chromosomes.
- Gains or losses in certain genomic regions known to be associated with childhood onset disorders.
Turn Around Time
3-4 days if performed in conjunction with direct fetal DNA isolation from amniotic fluid. (Please see below for specific prenatal specimen requirements).
Prenatal Specimen Requirements and Shipping/Handling
For Prenatal Samples
Amniotic Fluid: 30 mL of clear amniotic fluid or 2 T-25 flasks at 90% confluency. The sample also needs to be accompanied by 1-5 mL of maternal blood in EDTA (lavender top) for maternal cell contamination studies. Maternal buccal swab will also be accepted for MCC studies, please contact the lab for further information.
For POC Samples
Fetal tissue sample or villi or 2 T-25 flasks at 90% confluency.
Shipping:
Maternal Blood Sample
Store blood at 4°C until shipment. Ship at ambient temperature in an insulated container via overnight delivery within 96 hours of collection. Please contact the lab for maternal buccal swab options.
Amniotic Fluid
Store fluid at 4°C until shipment. Ship at ambient temperature in an insulated container via overnight delivery within 4 hours after collection.
POC Samples
Store fluid at ambient temperature. Ship at ambient temperature in an insulated container via overnight delivery within 24 hours of collection.
Send Specimen(s) to:
211. S Main Street
Suite AA
Orange, CA 92868
Tel: (714)288-3500
Required Forms
Test Limitations
Array CGH cannot detect certain chromosome rearrangements, such as balanced translocations or inversions, polyploidy, or intragenic mutations. Loss of heterozygosity is limited to the chromosomes 7, 11, 14, 15, 16 and 20, and is not evaluated or reported for any other region of the fetal genome.
GCPrenatal Array is a targeted prenatal array that only evaluates well known disease-causing regions of the genome that DO NOT include any adult onset disorders or adult-onset cancer predisposition syndromes.
CPT Codes
CPT’s: 81229, G0452
Maternal Cell Contamination CPT’s (Needed when DNA test is performed on amniotic fluid or CVS):81265, G0452