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Chromosome Analysis, Tissue

Test code(s) 14593X

This is an outdated version of this FAQ. It was effective 09/12/2013 to 09/21/2014.

The current version is available here.

Question 1. Multiple fetal anomalies were detected by ultrasound or autopsy, but chromosome analysis was normal. Are there further studies that can be done to test for a genetic disorder in the fetus?

Yes, there are other studies that may be appropriate. There are many causes of fetal anomalies, some of which are genetic. In the absence of clinical suspicion for a specific genetic disorder, a microarray analysis may be performed on the products of conception (POC) to detect subtle deletions and duplications (test code 90929, Chromosomal Microarray, POC, ClariSure® Oligo-SNP). If clinical suspicion exists for a specific disorder, there may be other genetic testing available. Please contact 1-866-GENE-INFO to discuss the case with a genetic counselor and for information on adding another test.

Question 2. My patient has a personal or family history of a chromosome abnormality. Chromosome analysis on products of conception tissue was reported as normal. Do these results guarantee that the fetus did not have the chromosome abnormality in the family?

No. Please call 1-866-GENE-INFO to discuss this case with a genetic counselor. Documentation of the specific genetic abnormality in the family will be necessary to determine the accuracy of the testing that was performed on the fetus.

Question 3. The tissue chromosome analysis was reported as a growth failure. Are there any other studies that can be attempted on the tissue to determine if the fetus has a chromosome abnormality?

When tissue fails to grow, a standard chromosome analysis is impossible to perform. There are two tests that may be considered to provide some information regarding the fetal chromosomes on tissue samples that fail to grow. FISH, Products of Conception Panel (test code 14820X) will provide information regarding the number of copies of chromosomes 13,16,18,21,22,X and Y. A Chromosomal Microarray, POC, ClariSure® Oligo-SNP (test code 90929) may be performed to detect subtle deletions and duplications of chromosome material. Please contact 1-866-GENE-INFO to discuss the case with a genetic counselor and for information on adding additional testing.

Question 4. Which chromosome abnormalities does the Chromosome Analysis, Tissue test  rule out?

  • Trisomies such as Down syndrome, trisomy 18, and trisomy 13
  • Sex chromosome abnormalities such as Turner syndrome and Klinefelter syndrome
  • Most rearrangements, including Robertsonian translocations and inversions
  • Marker chromosomes
  • Mosaicism above 14% (at a 95% confidence level)

Question 5. Which disorders cannot be detected by the Chromosome Analysis, Tissue test?

  • Most microdeletion syndromes, including DiGeorge, Prader-Willi, Angelman, Williams, and Smith-Magenis
  • Subtle rearrangements and small gains/losses
  • Mosaicism below 14%
  • Fragile X syndrome
  • Single gene disorders such as cystic fibrosis, Marfan syndrome, neurofibromatosis, etc

Question 6. The report indicates that maternal cell contamination (MCC) is a potential pitfall; is there a test that can be done to test for MCC?

Yes. Maternal Cell Contamination Study, STR Analysis (test code 10262) may be ordered on a maternal blood sample. Ideally, the maternal sample should be submitted with the tissue sample. If you are considering adding MCC studies to a completed case, please call 1-866-GENE-INFO to speak with a genetic counselor.

This FAQ is provided for informational purposes only and is not intended as medical advice. A clinician’s test selection and interpretation, diagnosis, and patient management decisions should be based on his/her education, clinical expertise, and assessment of the patient.

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