Reasons for Referral:

Prenatal CMA can be ordered for any patient who may be at increased risk for genetic disorders or has concerns about fetal genetic abnormalities. This test is only offered in conjunction with a karyotype analysis performed either in our laboratory or elsewhere. In addition, this test should be ordered only after the patient has had genetic counseling to review the detection rates, frequencies, and phenotypes associated with the syndromes detected by this assay. A copy of the signed patient request is required with the order.

Testing Methodology:

Prenatal Chromosomal Microarray Analysis (44K Oligo Array) utilizes array-based comparative genomic hybridization (aCGH) with approximately 44,000 oligos corresponding to 1476 known genomic locations attached to a glass slide. Genomic DNA from the test sample and a control sample are differentially labeled with fluorescent dye and hybridized to the oligos. Results are analyzed using quantitative imaging methods and analytical software to assist in identifying each targeted-DNA sequence as a loss of copy number (deletion), gain of copy number (duplication), or normal copy number. Please note: chromosome Analysis is required on every patient sample reffered for prenatal cma testing. the cost of prenatal cma will be in addition to the routine cost for cell cultures and chromosome analysis.

For fetal samples found to have a deletion or duplication by prenatal CMA, we confirm the finding by karyotype analysis and/or FISH at no additional cost. In some cases, additional CMA analysis of samples from both parents will be performed to provide the most complete and rapid interpretation of prenatal results. Therefore, parental blood samples are required for all prenatal CMA requests. Finally, comparative analysis of the fetal and maternal DNA will also be performed to detect significant maternal cell contamination of the fetal sample. It is our policy to report based on the analysis of the DNA from the direct fetal sample and to analyze the cultured fetal cells only if the direct results are inadequate.

Sensitivity:

This technology has been validated in our laboratory on many patients with known microdeletions or duplications and other abnormalities detected by traditional cytogenetic methods. It has also been validated on prenatal samples. CMA is limited to detection of gain or loss of genomic material. It will not detect balanced translocations, inversions, low level mosaicism or mutations that may be responsible for the clinical phenotype. Please refer to the detection rates for more information.

Consent Process Requirements:

It is necessary for the patient to read, understand, and sign the document entitled “Informed Consent for Prenatal Chromosome Microarray Analysis.” A copy of the informed consent document is available in each Prenatal CMA kit or may be obtained by calling 1-800-411-4363. It is strongly recommended and critical that the patient have pretest genetic counseling during which the information contained in the informed consent document is discussed and any questions addressed.

Specimen Requirements:

Genetic counseling is recommended and a completed consent process and signed consent form are required prior to ordering this test. Please submit these together with the Prenatal CMA requisition form and clearly specify which tests are ordered.

FETAL SPECIMENS:

1. AMNIOTIC FLUID ( two options available):
   • Option I: CMA and cytogenetic studies at BCM lab: 25-30 cc of direct fluid (gestational age >16 weeks) (Discard first 2 cc)
   • Option II: CMA only at BCM lab with cytogenetic studies elsewhere: minimally 15 cc of direct fluid (gestational age >16 weeks) (Discard first 2 cc)
     
2. CVS – ENTIRE FETALSAMPLE MUST BE SUBMITTED FOR BOTH CMA AND CYTOGENETIC STUDIES TO BCM LAB. Estimated 20-30 mg of chorionic villi (undissected) should be sent in sterile media.
   
3. FETAL BLOOD SAMPLE - PLEASE CONTACT THE LAB TO DISCUSS BEFORE COLLECTING SPECIMEN.
   
   PARENTAL BLOODS: 5-7 CC IN EDTA TUBE ON EACH PARENT. PLEASE NOTE: BLOOD SAMPLES FROM BOTH PARENTS ARE REQUIRED. FETAL SAMPLE WILL NOT BE PROCESSED UNLESS MATERNAL BLOOD SAMPLE IS RECEIVED WITH PRENATAL SAMPLE AND PATERNAL SAMPLE IS EITHER RECEIVED WITH FETAL SAMPLE OR SHIPPED IN 48 HOURS OR BCM LAB IS NOTIFIED OF UNAVAILABIITY OF PATERNAL SAMPLE .

Turnaround Time:

If the sample comes directly to the MGL Laboratory, analysis is performed without cell culture and the turnaround time is 5-9 days. If the direct analysis of amniotic fluid or CVS is not satisfactory, cells will be cultured to obtain sufficient DNA and turnaround time will be longer.

Shipping and Handling:

Please call 1-800-411-4363 prior to sending sample. Kits for submitting Prenatal CMA samples are available.

All tubes must be labeled with the patient’s name and date of birth, and a completed prenatal CMA requisition form and the original signed informed consent must accompany each sample. Ship specimens for overnight delivery at ambient temperature. Please notify the laboratory of incoming samples. Please call the laboratory to discuss billing for CMA.

CPT Codes:

For information on fees or CPT Codes for Prenatal CMA, please contact our Billing Office at 713-798-3295. Please contact our genetic counselors at 1-800-411-4363 prior to prenatal sample submission.

Forms:

 >> Prenatal CMA Requisition

References:

1. Cheung SW, Shaw CA, Yu W, Li J, Ou Z, Patel A, Yatsenko SA, Cooper ML, Furman P, Stankiewicz P, Lupski JR, Chinault AC, Beaudet AL (2005) Development and validation of a CGH microarray for clinical cytogenetic diagnosis. Genet. Med. 7:422-432.
2. Van den Veyver IB, Beaudet AL. Comparative genomic hybridization and prenatal diagnosis. Curr Opin Obstet Gynecol. 2006 Apr; 18(2): 185-91.
3. Lu X, Shaw CA, Patel A, Li J, Cooper ML, Wells WR, Sullivan CM, Sahoo T, Yatsenko SA, Bacino CA, Stankiewicz P, Ou Z, Chinault AC, Beaudet AL, Lupski JR, Cheung SW, Ward PA. Clinical implementation of chromosomal microarray analysis: summary of 2513 postnatal cases. PLoS ONE. 2007 Mar 28; 2: e327.
4. Sahoo T, Cheung SW, Ward P, Darilek S, Patel A, del Gaudio D, Kang SH,Lalani SR, Li J, McAdoo S, Burke A, Shaw CA, Stankiewicz P, Chinault AC, Van denVeyver IB, Roa BB, Beaudet AL, Eng CM. Prenatal diagnosis of chromosomal abnormalities using array-based comparative genomic hybridization. Genet. Med. 2006 Nov; 8(11): 719-27.

Test Code:

8636

Medical Genetics Laboratories
Baylor College of Medicine · Houston, TX 77030
Phone: 1-800-411-GENE · Fax: 713-798-6584
E-mail: