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Chromosome Analysis, Mosaicism

Test code(s) 14597X

Question 1. My patient has a personal or family history of a chromosome abnormality. My patient's chromosomes were reported as normal. Do these results guarantee that my patient does not have the familial chromosome abnormality?

No, please call Quest Genomics Client Services at 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 your patient.

Question 2. My patient has a developmental disorder. Chromosomes were reported as normal. Are there other genetic studies that can be done?

Yes, there are other studies that may be appropriate. There are many causes for development disorders, some of which are genetic. In the absence of clinical suspicion for a specific genetic disorder, a microarray analysis may be performed to detect subtle deletions and duplications. If clinical suspicion exists for a specific disorder, there may be other genetic testing available. Please call Quest Genomics Client Services at 866-GENE-INFO to discuss the case with a genetic counselor and for information on adding additional testing.

Question 3. What chromosome disorders does this assay rule out?

The Chromosome Analysis, Mosaicism test rules out the following:

  • Trisomies such as trisomy 21 (Down syndrome), trisomy 18, trisomy 13
  • Sex chromosome abnormalities such as Turner syndrome (45,X) and Klinefelter syndrome (47,XXY)
  • Most rearrangements, including Robertsonian translocations, reciprocal translocations, and inversions
  • Most marker chromosomes
  • Mosaicism above 6% (at a 95% confidence level)

Question 4. What disorders cannot be detected by this assay?

The Chromosome Analysis, Mosaicism test cannot detect the following:

  • Most microdeletion syndromes, including DiGeorge, Prader-Willi, Angelman, Williams, and Smith-Magenis syndromes
  • Mosaicism below 6% (at a 95% confidence level)
  • Fragile X syndrome
  • Single gene disorders such as cystic fibrosis, Marfan syndrome, neurofibromatosis, etc.
  • Very small or subtle chromosomal gains, losses, or rearrangements

Question 5. My patient has signs of a mosaic chromosome disorder (eg, pigmentation variation). Are there other studies that can be done to rule out a mosaic chromosome disorder?

Chromosome studies on additional sample types (such as skin fibroblasts) may be considered. Please call Quest Genomics Client Services at 866-GENE-INFO.

This FAQ is provided for informational purposes only and is not intended as medical advice. A physician’s test selection and interpretation, diagnosis, and patient management decisions should be based on his/her education, clinical expertise, and assessment of the patient.
Document FAQS.69 Version: 0
Effective 08/31/2012 to present